Apple Graphics Tablet
| Apple Graphics Tablet | |
|---|---|
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|
| Apple Graphics Tablet with the menu overlay in place | |
| Manufacturer | Apple Computer, Inc. (designed by Summagraphics) |
| Type | Graphics tablet |
| Release date | 1979 |
| Price | US$650 |
| Interface | Interface card in an Apple II expansion slot |
| Compatible | Apple II, Apple II Plus, Apple IIe |
| Model | A2M0029 (non-RFI version) |
The Apple Graphics Tablet is a digitising tablet for the Apple II. It was designed by Summagraphics and sold by Apple from 1979 at US$650; Summagraphics sold the same design for other computers as the BitPad.[1] The tablet and its wired pen connect to an interface card in one of the computer's expansion slots, and the tablet takes its power from the Apple II.[1]
Package contents
[edit | edit source]Apple's manual lists ten items in the box: the tablet with its attached cable, the pen with its cable, the interface card, a mylar "menu" overlay, two Graphics Tablet Software diskettes, a piece of die-cut double-sided foam tape, a warranty card, a packing list, the manual and a static cloth.[2]
The overlay goes in the centre of the tablet's recessed area. Part of it represents the Apple II's high-resolution screen and part is a menu of the software's functions; the software's menu-alignment routine tells the computer where the overlay has been placed.[2]
Installation
[edit | edit source]The owner's manual says the card works in any slot except slot 0 and suggests slot 5.[2] Apple's service procedures give the same rule for the Apple II and II Plus, and for the Apple IIe say the card works in any slot except slot 3.[3]
On the RFI version (below) the tablet and pen plug into short internal cables mounted on the computer's back panel, and those cables connect to the card. On the Apple IIe the two D-connectors fit the numbered openings in the back panel with nut plates; on the Apple II and II Plus they fit a two-piece metal connector clamp.[3]
Detecting the card
[edit | edit source]Programmers found the card by its firmware: with x as the slot number, the card's ROM holds $B0 at $Cx01 and $20 at $Cx09. The contributors to the comp.sys.apple2 FAQ who described this had not seen that signature in any other card's firmware.[4] The same Apple II Products Diagnostic diskette test that aligns the pen also runs a ROM test on the card (see Pen alignment below).[3]
RFI and non-RFI versions
[edit | edit source]The original tablet, model A2M0029, interfered with television reception, which mattered because the Apple II was designed to use a television as its display. A later model differed only in complying with the FCC's emission rules.[1] Apple's service documentation calls the two the non-RFI and RFI versions and describes the RFI tablet as functionally identical to the A2M0029, with "minor changes ... to meet EMI specifications required by the FCC".[3]
The RFI interface card has a different R1: 75 Ω (purple-green-black-gold) against 470 Ω (yellow-purple-brown-gold) on the non-RFI card. It also has a capacitor on the non-component side of the board. A service centre could repair a non-RFI tablet with non-RFI parts or upgrade it with the RFI parts below.[3]
| Part number | Description |
|---|---|
| 661-91140 | Graphics Tablet assembly, RFI |
| 661-91141 | Graphics Tablet interface card, RFI |
| 661-91142 | Graphics Tablet stylus, RFI |
| 590-0085 | Cable assembly, tablet, internal |
| 590-0102 | Cable assembly, stylus, internal |
| 825-0039 | Overlay, Apple Graphics Tablet |
| 600-8010 | Installation hardware assembly (Apple IIe) |
| 805-0085 | Clamp, rear peripheral interface connector (Apple II, II Plus) |
| 805-0105 | Clamp, front (Apple II, II Plus) |
Apple's schematic of the interface card is drawing 050-0020-02, dated February 1980.[5]
Care
[edit | edit source]The tablet is a solid wood base with a sheet-metal baseplate underneath and a moulded, snap-on plastic cover. Apple's instructions:[2]
- Clean the cover with a soft cloth and mild soap and water. Do not use abrasives or strong detergents.
- Keep magnets, disk drives, televisions, electric motors and large metal objects off the tablet. Strong magnetic fields disturb its magnetic orientation and make it malfunction.
- Keep diskettes off the tablet; its own magnetic field can erase them.
- Keep it out of direct sunlight and hot places such as a car boot, which warp the cover. Do not drop or jar it.
- If the interface card's edge fingers are dirty, clean them with a pencil eraser, or with cotton swabs and rubbing alcohol.
The pen's cable is fixed and short.[4]
Troubleshooting
[edit | edit source]Exposure to magnetic fields or rough handling can leave "dead spots" where the pen will not draw. Apple's manual describes these as a loss of magnetic orientation that a service centre can correct.[2] The service procedure is the biasing magnet in the symptom table below.
| Symptom | Cure |
|---|---|
| Monitor displays "not detecting interface card" | Check the interface card is firmly seated; clean the card's contacts; replace the interface card |
| Unable to draw or select menu commands with the pen | Swap, in this order: interface card, pen, internal pen cable, internal tablet cable, tablet |
| Apple IIe beeps when Graphics Tablet commands are typed | Press Caps Lock and retype the command; the software does not accept lower-case commands on the IIe |
| Erratic drawing: extra or missing dots | Wipe the tablet surface and the menu with the anti-static cloth. With the power off, draw the biasing magnet slowly across the surface in one direction, then repeat left to right, top to bottom and diagonally. Boot the Graphics Tablet Software and run MENU ALIGNMENT. If the tablet fails menu alignment, align the pen |
The biasing magnet can erase diskettes and video tapes. Keep it and the tablet away from both.[3]
Pen alignment
[edit | edit source]You need the Apple II Products Diagnostic Diskette (077-0100), the wooden pen alignment block, a nylon coil adjustment tool, a sheet of 1/8-inch Plexiglas and an anti-static cloth. Apple advises following these steps rather than the on-screen prompts, which sometimes describe the next screen.[3]
- Boot the diagnostic diskette. Select CARD TESTS, then GRAPHICS TABLET TEST.
- Press Esc and wait for the ROM test. If the ROM test fails, replace the interface card.
- Press Esc. Place the pen in the alignment block, and place the block so the pen is between the eighth and ninth lines of the "dots" column, counting the top border of the graph as line 1. Press Esc twice.
- Put the adjustment tool into the top of coil L2, in the upper left corner of the interface card. Turn the slug anticlockwise until it is level with the top of its sleeve, then clockwise until the crosshairs settle in the middle box. Keep turning until they disappear again.
- Turn anticlockwise until the crosshairs first settle in the middle box. Note the direction of the tool's blade.
- Keep turning anticlockwise. When the crosshairs jump out of the box, bring them back to where they settle and note the blade direction again.
- Set the slug halfway between the two positions.
Checking the tablet
[edit | edit source]With the surface biased, the menu aligned and the pen aligned:[3]
- Press Esc three times.
- Wipe both sides of the Plexiglas sheet with the anti-static cloth.
- Lay the sheet over the menu and, with a straight edge that is not metal, draw lines around the edges, through the middle and diagonally.
- There should be no gaps, double lines, glitches or stray dots. If there are, repeat the biasing and wipe the surfaces again. Apple's instruction for a tablet that still showed missing or extra dots was to send it to Apple.
Documentation
[edit | edit source]- Apple Graphics Tablet Operation and Reference Manual: owner's manual, 1979.
- Apple Graphics Tablet Technical Procedures: Apple's service procedures (installation, troubleshooting, pen alignment, RFI upgrade, parts list).
- Apple Graphics Tablet Interface Card Schematic (050-0020-02): interface card schematic.
See also
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 Ken Gagne, "Face-off: 1979 Apple Graphics Tablet vs. 2010 Apple iPad", Computerworld, 13 August 2010, https://www.computerworld.com/article/1546709/face-off-1979-apple-graphics-tablet-vs-2010-apple-ipad.html . Source for: designed by Summagraphics and sold by Apple for the Apple II; marketed by Summagraphics for other platforms as the BitPad; released 1979 at $650; powered from the Apple II; the original interfered with television reception and a later model differed only in FCC compliance.
- ↑ 2.0 2.1 2.2 2.3 2.4 Apple Computer, Graphics Tablet Operation and Reference Manual, 1979, hosted as File:Apple Graphics Tablet Operation and Reference Manual 1979.pdf. Chapter 1, "Getting Started": package contents, installing the interface card (any slot except slot 0, customarily slot 5), the menu overlay and menu alignment. Appendix A, "Care of the Tablet" and "If It Doesn't Work": construction, cleaning, magnetic fields, heat, cleaning the card's contacts, and dead spots.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 Apple Computer, Graphics Tablet Technical Procedures, from Apple Service Technical Procedures: Apple II/Apple III Archived Products, Volume Two (072-0231), hosted as File:Apple Graphics Tablet Technical Procedures.pdf. Section 1, Apple IIe installation, pp. 1.3-1.6; Section 2, Apple II or II Plus installation, pp. 2.3-2.8; Section 3, troubleshooting: symptom table p. 3.3, pen alignment pp. 3.4-3.5, checking the tablet p. 3.5; Section 4, RFI upgrade, pp. 4.2-4.5; Section 5, illustrated parts list, p. 5.2.
- ↑ 4.0 4.1 Oliver Schmidt and Guillaume Tello, answer 013, "How do I write programs for the Apple Graphics Tablet?", in Csa2 Apple II FAQs: Input Devices (Csa2KBPADJS.txt), comp.sys.apple2 Usenet FAQ, https://gswv.apple2.org.za/a2zine/faqs/Csa2KBPADJS.html . Source for the firmware signature and for the short pen cable. Community FAQ, cited as a secondary source.
- ↑ Apple Computer, Schematic, Graphics Tablet Interface, drawing 050-0020-02, 2/80, with a cover sheet from David T. Craig's collection, hosted as File:Apple Graphics Tablet Interface Card Schematic 050-0020-02.pdf.