[continued from previous message]

the computer's composite and RF video output signals are 2 (OS graphics mode 0), 3 (no corresponding OS graphics mode), and F (OS graphics mode 8). Each
of these modes has a pixel resolution of one half color clock by one scan
line. They are generally considered to have one color and two luminances.
With the use of artifacts, pixels of four different colors can be displayed on the screen in each of these modes. Artifact colors are absent when using separate chrominance and luminance video output signals.

With a PAL Atari, varying the amplitude of the luminance signal at twice the color clock frequency means about 7.08MHz. This frequency does not have a simple mathematical relationship to the PAL color subcarrier frequency of 4.43MHz. As a result, while some artifacting effects may be seen, there are no stable artifacting colors as seen on NTSC systems.

With a SECAM Atari, color information is encoded using frequency modulation rather than using a color subcarrier frequency, so there is no possibility of artifacting as seen on NTSC systems.

Recommended readings:
- http://preview.tinyurl.com/qhyr6pg
- http://atariage.com/forums/topic/275882-atari-800-ntsc-artifacting/

------------------------------

Subject: 2.6) What is HDTV display lag?

Much software on the 8-bit Atari is highly interactive and timing-critical.
For example, many games are highly responsive to input from the game player
via a game controller (such as a joystick). The Atari software programmer
can reasonably assume that the video display device can reflect changes as output by the Atari with no perceivable additional delay. Software timing considerations are normally limited to the capabilities and constraints of
the Atari hardware itself.

However, in some cases a television or video monitor may introduce a
noticeable lag time between the video signal as input by the Atari, and the video signal as actually displayed by the device. While any such effect is truly negligible with CRT televisions or monitors (the standard of the time of the Atari), the modern high-definition television (HDTV) has emerged as an important exception. An HDTV typically dedicates considerable processing efforts (hardware+software) toward presenting the most attractive picture possible. Since few HDTV applications require precise interactive timing,
this video processing is generally not optimized for time efficiency. When used with an older but timing-precise device such as an 8-bit Atari computer, the resulting delay can be quite noticeable, making the HDTV essentially unusable for "serious" action gaming.

Fortunately, many HDTVs offer a "game mode" that circumvents much of the video processing otherwise performed, thereby eliminating most of the display lag otherwise introduced by the television. If an HDTV is to be used with the Atari for gaming, a "game mode" on the HDTV is essential.

Wikipedia on the topic: http://en.wikipedia.org/wiki/Display_lag

------------------------------

Subject: 3.1.1) What are the Atari 410, 1010, XC11, & XC12 Program Recorders?

An Atari Program Recorder resembles an ordinary audio cassette tape player, providing secondary (not directly accessible by the computer's central processing unit) and offline (removable from the computer) magnetic storage
and retrieval of digital data, using a standard (analog) compact cassette.

While the computer converts digital serial data into analog audio tones for recording/saving directly to cassette, the program recorder contains analog to digital circuitry for converting analog audio tones to digital serial data
when playing/reading from cassette.

In addition to the digital information track, the program recorder can also play back an audio track, allowing the computer user to both load/run programs and listen to voice or music.

Under the Atari Operating System, the digital storage capacity of a 60-minute cassette is about 102,400 bytes (100KiB). The Atari OS writes files in fixed- length blocks at 600 baud (physical bits/second).

Atari program recorders use SIO Motor Control; only one such device can be attached to the system at a time.

Specifications common to all Atari program recorders:
- Tape structure is standard 1/4 track stereo format:
- 4 tracks, divided into 2 channels/sides ("Side A" and "Side B")
- Each tape channel/side is stereo, consisting of 2 tracks:
- Left / Audio track
- Right / Digital track (audio frequency-shift keying (AFSK))
- Digital track consists of two tones: "mark" = 5327 Hz ; "space" = 3995 Hz
- Automatic/software motor control: the computer can control tape motion
start/stop (both play and record functions), if the recorder PLAY button
has already been pressed by the user.
- Tape speed: 1.875 IPS (inches per second)
- 3-digit tape counter
- Any audio track plays through the television/monitor speaker, by way of
the computer's audio output.
- Preset volume levels (both playback and recording)
- Media used is the Philips Compact Cassette or equivalent, containing
Type I / ferric oxide / normal bias cassette tape.
(Atari CX4100 Blank Cassettes - 12 Pack never shipped.)
- Type II ("chrome") or Type IV ("metal") cassette tapes are not used
with Atari program recorders. See: http://preview.tinyurl.com/jgbm9p7
- Cassettes can play/record on both sides -- cassette must be removed,
flipped-over, and re-inserted to access the reverse channel/side of the
tape.
- Cassette write protect notch status is respected -- will not write to a
cassette side missing the write protect notch corresponding to that side
of the cassette.
- The cassette utilization/filesystem is controlled entirely by software,
normally the C: Cassette Handler of the Atari Operating System.
Specifications are provided elsewhere in this FAQ list.
- Only one program recorder can be operated on the Atari SIO bus.

410 Program Recorder
- Shipped with the earliest (1979-1980) 800 computer systems
- Was also included in the kit: CX482 The Educator
- Connectivity: Built-in SIO cable - must end SIO daisy chain
- Produced 1979-1983. Replaced by the 1010.
- Manuals:
- Atari 410 Program Recorder Operator's Manual C014810
(shipped with earlier units)
- Atari 410 Program Recorder Owner's Guide C060055
(shipped with later units; USA or International (Holland) printings)
- 3 main versions, each with two different variations:
1) Unreleased prototype 410 version
- Small/narrow profile
- Chrome carrying handle
- "Atari 410" label between cassette bay door and buttons
- Above cassette bay door, left to right:
Atari logo, tape counter, "Program Recorder"
- 6 Buttons, left to right:
Rewind, REC, Play, Advance, Stop, Eject
- Two unreleased prototype version variations:
1a) Buttons are black, except red REC button
2a) Buttons are white with black borders
See: http://www.rhod.fr/images_periph/410/410proto.jpg
2) Made in Japan by Bigston (initial production version)
- Carrying handle
- "Atari 410" label between cassette bay door and buttons
- Tape counter also between cassette bay door and buttons
- 5 Buttons, left to right:
Record (red label), Rewind, Play, Advance, Stop/Eject
- Two Japan 410 version variations:
2a) 120V Made in Japan version
Power: plugs directly into wall (120V AC, 6W)
2b) 220V/240V (Direct Current) Made in Japan version
Power jack on the RIGHT side of the unit. Center positive.
Power: Used with an external DC power supply rated for 6.0V DC
and 300mA, such as the Tadmod 6498 or Atari AC/DC Adapter Type
FW3199 (both detailed elsewhere in the FAQ list) or equivalent.
3) Made in Hong Kong by Transtek or by Chelco Sound (Hong Kong) Limited
- No carrying handle
- "Atari 410" label on cassette bay door
- Tape counter above cassette bay door
- 6 Buttons, left to right:
REC, Play, Rewind, Advance, Stop/Ej., Pause
- Two Hong Kong 410 version variations:
3a) 120V 60Hz 7 watts Made in Hong Kong version
Power: plugs directly into wall (120V AC, 6W)
3b) 220V/240V (Direct Current) Made in Hong Kong version
Power jack on the BACK of the unit. Center positive.
Power: Used with an external DC power supply rated for 6.0V DC
and 300mA, such as the Tadmod 6498 or Atari AC/DC Adapter Type
FW3199 (both detailed elsewhere in the FAQ list) or equivalent.
- C015705 REV3 Atari sales flyer reads: "Two styles of the Atari 410
Program Recorder are currently manufactured, with equivalent performance."
This refers to versions #2 and #3 above.
- Technical manuals:
- Atari 410 Program Cassette Recorder Field Service Manual FD100004
- Atari 410 Program Cassette Recorder Field Service Manual PAL-UK FD100005

1010 Program Recorder
- Produced from 1983-1984. Replaced the 410.
- Connectivity: 2 Atari SIO ports for direct connection to Atari computers
- Shipped with SIO cable CA014122 (3-foot)
- Manual: The Atari 1010 Program Recorder Owner's Guide C061133
- Two slightly different versions were manufactured:
- 1010S. FCC ID: BPA99H1010
- Made in Japan by Sanyo
- 6 Buttons, left to right:
Record, Play, Rewind, Advance, Pause, Stop/Ej
- Orange sticker inside cassette bay
- 1010C. FCC ID: BPA7YJ1010
- Made by Chelco Sound (Hong Kong) Limited
- 6 Buttons, left to right:
Record, Play, Rewind, Advance, Stop/Ej, Pause
- Silver sticker inside cassette bay
- Power: Used with an external 8.5 to 9 volt AC transformer power supply
rated for at least 8 watts; Atari C061515 or C061516 or equivalent.
(Equivalents include the Atari CA014748 and CA017964.)
- In early production units the power indicator lights as soon as the
power adapter is plugged in. In later models the power indicator will
only light after you press Play, Rewind or Advance.
- Technical manual:
Atari 1010 Cassette Recorder Field Service Manual FD100223
- Rev. 02 April 1983
- Rev. 02 September 1983

XC11 Program Recorder
- Replacement for the 1010.
- Available in the UK from winter 1986 to summer 1986 (Atari User), when it
was replaced by the XC12. Very limited 1986-1987 release in the U.S.
- Connectivity: Has a built-in SIO cable and one free SIO port
- Power: Drawn from SIO pin 10 (+5V/Ready)
- Made in Japan

XC12 Program Recorder
- Replacement for the XC11 (or for the 1010 in markets where the XC11 was
never released).
- Shipped in mid-1986 in the UK. Wide distribution internationally, though
never introduced in the U.S.
- Also included in the 130XE Starter Pack (UK):
- 130XE + XC12 + CX40 Joystick + TX9043 Compilation Tape
(Typo Attack, Missile Command, Centipede, Tennis, Star Raiders)
- http://www.rhod.fr/ataripics/130xestarter.JPG
- Also included in the XEgs kit, XE 2012 (France)
- "Round" window
- Based on the Phonemark PM-4401A
- Printed circuit board is marked "PM4401-4"
- Connectivity: Built-in SIO cable - must end SIO daisy chain
- Power: Drawn from SIO pin 10 (+5V/Ready)

------------------------------

Subject: 3.1.2) What other cassette recorders can I use with my Atari?

Important contributor to this section: Tomasz Krasuski

Unlike other microcomputer systems of the time period, only Atari-specific cassette tape recorders could be used with Atari 8-bit computers. Several
such peripherals were produced by companies other than Atari:

Compu-Mate Computer Data Recorder by General Electric (GE, G.E.)
- 3-5148A (unit) / 3-5156 (box)
- 3-5149A Atari/Commodore Interface Module (IFM)
- 1st data cable: Data Recorder <-> IFM Interface or Data Recorder <-> C64
- 2nd data cable: IFM Interface <-> Atari computer SIO connector
- Monophonic -- No support for audio track as supported by other program
recorders for the Atari
- No second SIO port - must be at end of SIO chain
- Battery operated or uses an external power supply
- Switch on the bottom, Atari or "All other computers".
- More info: http://www.atariage.com/forums/index.php?showtopic=128505
- Pics: http://www.atariage.com/forums/topic/161936-atari-1010-problem/

Phonemark PM-4401A and derivatives
- Manufactured for Atari as the Atari XC12
- "Round" window and "notched" top case design
- No second SIO port - must be at end of SIO chain
- PM-4401A by Phonemark
- Top of unit: "Phonemark" in white lettering on black label
- Bottom of unit: "Computer Cassette Data Unit"
- Box: Blue background, "Phonemark Computer Cassette" "PM-4401A"
"Suitable For Use With Atari Home Computer"
- XG12 [by Phonemark for Datamark]
- Atari XE case color
- Top of some units: "Datamark XG12" in red lettering
- Top of other units: Black label, no branding
- Bottom of unit (some): "Datacorder" on gold label
- Box: Datamark DM-6402A (see below). These units seemingly sometimes
shipped by Datamark as a substitute for their own DM-6402A.
- See below for the Datamark-derived version of the XG12.
- TurboData [by Phonemark for ?????]
- Atari XE case color
- Built-in Turbo upgrade???
- Top of unit: "TurboData" in red lettering on white label
- Box unknown
- XL12 [by Phonemark for Logical Design Works (LDW) on behalf of Atari]
- Atari XE case color
- Top of some units: "For Atari XL12" in red/silver
- Top of other units:
"For Atari XE, 800XL" in white lettering on black label
- Bottom of some units: "Computer Cassette Data Unit" "Model No XL12"
- Bottom of other units: "For Atari"
- Box: Atari-like, with red strip down ONE side of box, "XL 12" in large
font (with space in middle), "XC12" mistake in smaller type, "For
Atari" does NOT use Atari logo font, Phonemark unit is pictured
- Utilized parts supplied by Atari, after Atari discontinued their own XC12
- Sold in Chile by Coelsa (official Atari importer) and in Eastern Europe
- Replacement for the Atari XC12; would be replaced in Europe by the XCA12
- See below for Datamark-derived version of the XL12.
- XCA12 [by Phonemark for California Access (brand of LDW) on behalf of Atari]
- Atari XE case color
- Top of unit: "For Atari Computer" in black/red/black, "XCA12" in silver
- Bottom of unit: "For Atari Computer" "Model Number XCA12"
- Box: Atari-like, white with orange strip down one side of box,
"For Atari Computer" with Atari logo font
- Front (very small pic): http://img.archiwumallegro.pl/?876820703
- Rear: http://preview.tinyurl.com/ogh8j9p
- Utilized parts supplied by Atari, after Atari discontinued their own XC12
- Sold in Eastern Europe, especially Poland
- Replaced the XL12; would be replaced by the CA-12 (once Atari parts
supply was exhausted)
- CA-12 [by Phonemark for California Access (brand of LDW)]
- Atari XE case color
- Top of unit: "For Atari Computer" in black/red/black, "CA12" in silver
- Bottom of unit: "For Atari Computer" "Model Number CA12"
- Printed circuit board has the markings "P.M." "4401-5" "REVB"
- Box: White with Orange highlights, "CA-12 Program Recorder"
http://www.aceton.pl/images/105338.jpg
- Sold in Eastern Europe, especially Poland
- Replacement for the XCA12 (produced independently of Atari)

Datamark DM-1301A
- Similar dimensions to Phonemark PM-4401A and derivatives, but even more
Atari-inspired case styling includes slanted lines matching those of Atari
XE computers and peripherals.
- Top of unit: "Datamark" in red lettering
- Unit pictured in center:
http://www.retrogames.cl/imagenes/varios/zz/caseteras.jpg
- Box: Atari-like, with red stripes down BOTH sides
- Box pictured at upper-left:
http://www.retrogames.cl/imagenes/varios/zz/casencaja.jpg

Datamark DM-6402A and derivatives
- "Square" window and "un-notched" top case design
- No second SIO port - must be at end of SIO chain
- DM-6402A by Datamark
- Atari XL case color, black label (unlabeled), black buttons
- Units exist????
- Box: Black background, "Datacorder Unit" in yellow, "Model DM-6402A" in
orange", "Power Without the Price" in red
- XG12 by Datamark
- Atari XE case color
- Top of unit: "Datamark XG12" in red lettering
- Box: Datamark DM-6402A (see above)
- See above for the Phonemark-derived version of the XG12.
- XL12 [by Datamark for Logical Design Works (LDW) on behalf of Atari]
- Atari XE case color
- Top of units: "XL12" in silver
- Top of some units: "For Atari" in silver/red
- Bottom of some units: "Datarecorder" "For Atari Computer" "DM-6402A"
- Bottom of other units: "For Atari"
- Box: Atari-like, with red strips down BOTH sides of box, "For ATARI" uses
Atari logo font, features photo of Datamark original version unit
- Utilized parts supplied by Atari, after Atari discontinued their own XC12
- Sold in Chile by Coelsa (official Atari importer) and in Eastern Europe
- Replacement for the Atari XC12; would be replaced in Europe by the XCA12
- See above for the Phonemark-derived version of the XL12.
- NA-R25 Najm [by Datamark for aDawliah Universal Electronics APL]
- Atari XE case color
- Top of unit: "Najm NA-R25" in red lettering
- Box: Datamark DM-6402A (see above)
- Substitute for the Atari XC12 in later 65XE Najm packages

Taihaho Computer Cassette
- Box: Taihaho Data Cassette Recorder/Player
- 120V version (red) for North America or 240V version (black) for UK
- Photos in this AtariAge Forums thread: http://preview.tinyurl.com/nxfabz9
- Built-in SIO cable - must end SIO daisy chain
- Power supply is built-in (plugs directly into the wall)

LINKS
http://computers.mcbx.netne.net/8bit/aptaperec/index.htm

------------------------------

Subject: 3.1.3) What speed upgrades are there for Atari program recorders?

Numerous methods were created for upgrading the (painfully) slow data transmission speed of the Atari program recorders. Most of these originated
in regions of the world where program recorders were normally used with the Atari rather than (extremely expensive) disk drives.

- CASA Turbo Tape, by CASA (Dutch) (1985)
o Purely software
- Rambit TurboCharger (1986?)
o From the UK
o For: 410, 1010, XC11, Phonemark, XC12
o Circuit board + conversion utility program on cassette.
The software is used to convert standard Atari data cassettes to Rambit
format cassettes.
o 3300-3600 bit/s achieved
o Review (Nov/Dec86): http://www.page6.org/archive/issue_24/page_30.htm
- Turbo 2000, by Jiri Richter (RICO or JRC; Czechoslovakia)
o Project published in Zpravodaj Atari Klubu -- priloha 11/1987
See: http://blog.3b2.sk/igi/file.axd?file=2013%2f12%2fTurbo+2000.pdf
o Software + modification project for XC12
o Transfer rates flexible; later standardized to 2270 baud
o Software: Super Turbo cartridge software by RICO (1988)
o Released later: TT-DOS, a DOS 2.5 clone with high speed tape handler, B:
o TT-DOS 1.1 (c) 1989 JR Computing (JRC)
o TT-DOS 1.2 (c) 1989 JR Computing
o TT-DOS 1.5 (c) 1991 JR Computing
o Released separately (West Germany): B-TAPE high speed system by Jiri
Bernasek (BEWESOFT) for use with BW-DOS or SpartaDOS
o Released separately (Poland): K.S.O. 2TO6 ("KSO Turbo 2000")
- "Cassette Operating System" (L1, L2, WIELOBLOK) software by
Wojciech Zabolotny
- Published in the magazine IKS 11/1988 pages 4-6, with follow-up
information published in the next issue 12/1988 page 14 and in
01/1989 pages 28 and 31.
- Reviewed in Bajtek 8/89 (compared with AST)
- Separately: K.S.O. Turbo 2000 cartridge project for self assembly
o Turbo 2000 format extensions (all from Poland):
- Turbo 2000F+ or "New format"
- Speedy 2007 or "*AJEK" (translates to "*Thanksgiving")
- Turbo 2000F, by MUEL (1989)
o 6700 baud. Advertisement: Bajtek 8/1989 p26
- Turbo 2001 (TOMS)
- Turbo 2002
- Turbo 2000 Plus
- Atari Super Turbo (AST) (late 1987)
o Designed by Slawomir Nienaltowski (designer of the SN-360 disk drive),
sold to Atari Studio (AS; later: Mirage)
o The first Polish Turbo system
o Programs stored with AST can be read by Turbo 2000.
o Originally for the 1010, later released for XC12 and clones.
o Reviewed in Bajtek 4/89
o Later version(s) sold with software on cartridge: AST Turbo Cartridge
- Turbo 6000 / Schleife '88 (Loop'88)
o From East Germany, for XC12
o Chaos System: Turbo 6000 interface + software: Chaos Loader, Chaos Copy
o 6000 baud
- Injector / Fast Injektor
- Hardware (for the XL12) + software
- Developed by Pedro P. Caraball Alvarez (Turbo Software, Argentina/Chile)
- Version 1.0 05/09/88 for Turbo Software, published by M.P.M. S.A. (Chile)
- Rights sold to Coelsa (official Atari importer in Chile) in 1990. Coelsa
would sell many XL12 units with the Fast Injektor preinstalled.
- 4000 baud
- http://www.retrogames.cl/injektor.html
- STAC / Super Turbo Auto Corrector
- From Argentina by Jorge Cwik (ijor), 1988
- Purely software, with error recovery
- Available (sources): http://preview.tinyurl.com/ybrbt8qf
- SITRE/S.I.T.R.E./"Sistema Inteligente Turbo con Recuperacion de Errores"
o From Chile by Victor Parada G. (++Vitoco)
o Purely software. Primarily a copying tool, but also turbo speed.
o Version 1.01 March 1989 via SYFCOM, then VCC (Video Compu Club) for 800XL
o Version 2.01 April 1989 for 130XE
o Version 1.11 June 1989 (800XL, attempted support for longer programs)
o Version 3.02 (2015, full support for XL/XE 64KiB to 320KiB)
o Available: http://www.vitoco.cl/atari/sitre/
- Turbo 2600, by Zaklad Elektroniczny SZOK (Poland)
- Blizzard Turbo, by Atares (Poland, 1989)
- Software v1: Microloader, Turbo KOS, Short KOS, Looking
- Software v2: KOS+, Blizzard Turbo, Blizzard Copy, 3 Microloaders
- Available separately: BIG2 cartridge by KNS Corporation
- Turbo ROM, jointly developed by PLUS and MAPASOFT (Poland) (1991?)
o Special software cartridge loader required to read such cassettes
o Reviewed in Tajemnice_Atari 5/91
- Hard Turbo (Poland)
Most of the above upgrades are described in detail at: http://atariki.krap.pl/index.php/Systemy_turbo

------------------------------

Subject: 3.2.1) What is the Atari 810 Disk Drive?

Portions of this section developed by Laurent Delsarte from the 810 Field Service Manual.

The Atari 810 is a floppy disk drive that provides secondary (not directly accessible by the computer's central processing unit) and offline (removable from the computer) magnetic storage and retrieval of digital data, using a standard (of its time) 5.25 inch diskette. Diskette storage capacity is
90KiB. The 810 Disk Drive is used with a single Atari 8-bit computer with a minimum of 16KiB of RAM installed. Up to four 810 disk drives may be attached and used with an Atari computer at the same time.

- Connectivity: 2 Atari SIO ports for direct connection to Atari computers
- Shipped with SIO cable CA014122 (3-foot)

The front of the 810 features a Power on/off switch, a "Power" indicator
light, and a "Disk busy" indicator light. The rear of the unit includes two SIO ports ("I/O Connectors"), a power input jack, and drive number selector switches:
Black & White left: Drive 1
Black right, White left: Drive 2
Black & White right: Drive 3
Black left, White right: Drive 4

810 Performance Specifications
- Capacity per diskette:
40 tracks x 18 sectors/track = 720 sectors/disk
720 sectors x 128 bytes/sector = 92,160 bytes/disk (90KiB)
- Average Data Transfer Rate: 6000 bit/s
- Average Latency: 100 milliseconds
- Track to Track Access Time: 5 milliseconds
- Average Access Time: 74 milliseconds
- Head Settling Time: 15 milliseconds
- Head Loading Time: 35 milliseconds
- Power-up Delay: 0.5 seconds
- Maximum Data Access Time: 236 milliseconds

810 Functional Specifications
- Disk Rotation Speed: 288 RPM (Revolutions Per Minute) +- 1%
(range: 285.12 - 290.88 RPM)
- Recording Density: 2,938 BPI (Bits Per Inch) (maximum)
- Flux Density: 5,876 FCI (Flux Changes per Inch) (maximum)
- Track density: 48 TPI (Tracks Per Inch)
- Tracks: 40 (track 1 is the outermost; track 40 is the innermost)
- Encoding method: Frequency Modulation (FM, or "single density")
- Drive heads: One (accesses the disk from below)
- Disk type used is the Atari CX8100 Blank Diskette or equivalent, which is
an industry standard 5.25" micro-diskette / minidiskette / mini-disk /
minifloppy diskette / mini-floppy diskette / floppy disk.
(Atari specification: C016884)
- Any one of the following certifications/marketing labels is in itself
sufficient to indicate 5.25" disks suitable for use with the Atari 810:
40 tracks, 48 TPI, Single Density (SD/1D),
Double Density (DD/2D), Quad Density (QD/4D)
- Exception: Early disks with room for only 35 tracks at 48 TPI, the
original configuration for the format as introduced in 1976. Such 35
track disks have a noticeably smaller-length drive head access opening
than the eventual standard 40 track disks, which were introduced in
1977. Production of disks supporting only 35 tracks was discontinued
by the end of 1980.
- NOTE: High Density (HD) 5.25" floppy disks (very commonly used for the
MS-DOS 1200KiB format introduced with the IBM PC/AT in 1984) can NOT be
used with Atari 810 and compatible drives.
- Soft-sectored disks or hard-sectored disks may be used. The sector holes
of hard-sectored disks would be ignored by the 810, so hard-sectored
disks are unnecessary and very rarely used with the Atari.
- Single-sided (SS/1S) or Double-sided (DS/2S) disks may be used.
- The 810 is a single-sided drive (one drive head). A disk is inserted
into the drive with label side up and, from below, the drive head
accesses the back (non-label) side media surface via the access
opening on the back side of the disk.
- All disk media is actually two-sided, and all disks have drive head
access openings on both the front and reverse sides of the disk (so
that a drive head can access the disk media from either side).
"Single-sided" disks are certified for use on only one side (either
side), while "double-sided" disks are certified for use on both sides.
- The reverse side of a disk (the front, label side media surface) may
be accessed by the 810 by re-inserting the disk into the drive upside-
down, label side down. The 810 thus sees the reverse side of the disk
as another, entirely different, single-sided disk. (Rare "flippy"
disks, with two index holes/timing holes, support this for single-
sided drives that use the index hole/timing hole; the 810 ignores the
index hole/timing hole so a "flippy" disk is not needed.)
- Diskette write enable notch status is respected: will not write to diskette
side lacking (or having a covered) write enable notch corresponding to that
side of the disk.
- On the Atari, an empty floppy disk drive is powered on prior to inserting a
diskette into the drive. Conversely, the diskette is removed from the drive
before the drive is turned off. These procedures protect the integrity of
data on diskettes.

810 Internals
- 6507 microprocessor (MOS Technology MCS6507 or equivalent) @ 500KHz, C010745 - ROM, C011299 (some chips marked C001299)
- 6810 128 x 8 bit static RAM (1KiB) (Motorola MCM6810), C014328
- 6532 PIA (MOS Technology 6532 RAM-I/O-Timer (RIOT) or equivalent), C010750
- Western Digital FD1771 Floppy Disk Controller (FDC) @ 1MHz, C014329
- Read/Write Head Gap: .013 inches
- Guard Band: .008 inches
- Pad Pressure: 17 grams

810 industrial design (case): Roy Nishi and Russ Farnell

The 810 underwent several significant design revisions over the course of its manufacture.

Original 810 Disk Drive (1980-1981, no Data Separator and "Pre-Analog") specifications:
- Micro Peripherals, Inc. (MPI) minifloppy diskette drive mechanism
- Two printed circuit boards: a Side Board and a Rear Board
- Power Input: 9 volts AC, 1.7 amperes
- Power Usage: 20-21 watts
- Power: Used with an external 9 volt AC transformer power supply:
Atari CA014748 or equivalent (including the Atari CA017964). (Later/most
810 units, those with a Data Separator installed, require the more capable
Atari CA017964 or equivalent.)

810 drives manufactured after September 1, 1981 ("DS" sticker) shipped with an External Data Separator Board, which improves the drive's ability to distinguish between data pulses and clock pulses on the disk, lowering the chance of a misread. It is installed in the Side Board where the FDC chip would otherwise be installed. (810 Field Service Manual p.1-9) The Side Board stepper motor circuit voltage was increased to regulated 12 volts DC as well, leading to greater power requirements for the drive:
- Power Input: 9 volts AC, 3 amperes
- Power Usage: 30 watts
- Power: Used with an external 9 volt AC transformer power supply:
Atari CA017964 or equivalent
The External Data Separator Board was also offered as an upgrade for earlier 810 drives. Earlier Side Boards must be upgraded in order to accept the Data Separator.

Next, Atari introduced the 810 Revision C ROM in November 1981 ("C" sticker). According to Antic (Oct. 82), "ROM C causes diskettes to be formatted with an improved sector layout which is more efficient than that used by earlier 810 control ROMs." Performance was reported to be 20% faster than with the original B ROM. The ROM C was also offered as an upgrade for older drives.

810 drives produced from February 1982 used the new "810 Analog"
("810M Analog") design, further improving reliability:
(see 810 Field Service Manual p.8B-1)
1. A Power Supply Board now bolts onto the common base plate where the Rear
Board used to be. The Power Supply Board contains:
a) A redesigned Power Supply.
b) A Tachometer/Speed Switch I.C. (frequency to voltage converter)
added as the Tach circuit to stabilize the motor speed.
2. An Analog Board now bolts to the top of the Drive Mechanism. This board
contains the Analog circuitry which used to be on the Rear Board. The
major changes are to the Read/Write circuitry. The Analog Board
contains:
a) Operational amplifiers ("op-amps") and discrete transistors in place
of transistor arrays.
b) A multiplexor chip for switching the Read/Write amplifiers.
3. A 10 pin ribbon cable connects the Analog Board to the Power Supply
Board.
810 Analog power: Used with an external 9 volt AC transformer power supply
rated for at least 30 watts; Atari CA017964 or equivalent.
The 3 new 810 Analog components were also offered together as an upgrade:
- CB101128 "Grass Valley Analog Board Set" for Pre-Analog 810 drives.

In November 1982, the drive mechanism of the 810 Analog disk drive was changed from MPI to Tandon. The Tandon version is known as the "810T Analog" disk drive.

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