Apple III Plus
 | |
| Apple III Plus with Monitor III | |
| Specifications | |
|---|---|
| Manufacturer | Apple Computer, Inc. |
| Type | Business personal computer |
| Released | December 1983 |
| Discontinued | April 1984 |
| Intro price | US$2,995 for the 256 KB system (A3S1256), February 1984 |
| CPU | Based on the 6502B with extended addressing; 2 MHz peak, 1.4 MHz average |
| Memory | 256 KB as sold (minimum 128 KB; SOS supports 512 KB). 4 KB ROM for initialisation and diagnostics |
| Storage | Built-in 5.25-inch drive, 143,360 bytes per diskette; up to three more on a daisy chain; ProFile hard disk via an interface card |
| Display | 40×24 and 80×24 text, 40×24 in 16 colours, 560×384 text interlace; graphics 280×192 mono, 280×192 in 16 colours, 140×192 full 16 colour, 560×192 mono |
| Sound | 6-bit DAC with 64 volume levels, a one-bit square-wave generator and a fixed-frequency beep |
| Dimensions | 44.45 cm wide × 46.23 cm deep × 12.19 cm tall |
| Weight | 11.8 kg (26 lb) |
| OS / Firmware | Apple SOS 1.2; Apple III Business BASIC; Apple II emulation mode |
| Predecessor | Apple III |
| Model no. | A3S1256 (256 KB system) |
The Apple III Plus is the last model of the Apple III. Apple built it from December 1983 to April 1984.[1] Apple's February 1984 dealer price list gives $2,995 for the 256 KB Apple III Plus system, against $2,695 for the 256 KB Apple III system.[2] It uses the Apple III case, processor, disk drive, audio hardware and expansion slots, and adds a clock/calendar as standard, a text interlace mode and a revised keyboard.[3][4]
Differences from the Apple III
[edit | edit source]The two owner's guides give the differences in their specification appendices.
| Apple III | Apple III Plus | |
|---|---|---|
| Keyboard | 74 keys: 61 main, 13 numeric pad. Four special keys: TAB, ESCAPE, RETURN, ENTER | 75 keys: 62 main, 13 numeric pad. Five special keys: TAB, ESCAPE, RETURN, ENTER and DELETE |
| Standard memory | 128 KB | 256 KB as sold; the guide states a minimum of 128 KB |
| Ambient temperature | 15 to 35 °C | 0 to 45 °C |
| Power supply | +5, −5, +12, −12 V, 100 W maximum, "UL approval pending" | Same rails, 1 A, 100 W maximum, UL/CSA approved |
| Text modes | Three | Three, with text interlace at 560×384 in 80-column mode |
| Clock/calendar | Optional (Apple III Clock Kit) | Standard, powered by three AA cells inside the cover |
The case, weight, processor, clock speed, 4 KB ROM, audio hardware, video outputs and four expansion slots are the same on both machines.[5][3] The Apple III guide gives the upper temperature limit as 35 °C because of "the deformation temperature of diskette cases";[5] the III Plus guide gives 0 to 45 °C and names "the temperature at which disk case can warp" as the critical factor.[3]
The two keyboards have different layouts and are not interchangeable, although most keyswitches are the same; the III Plus uses only the Alps long-stem keyswitch.[7] Apple later stopped supplying the Apple III keyboard as a spare: an order for one was filled with a III Plus keyboard, keyboard cover and encoder ROM (341-0136 or 342-0136, replacing 341-0034).[8]
Clock/calendar battery
[edit | edit source]The clock/calendar runs on three AA cells in a battery clip between the power supply and the speaker, on the front wall of the computer well, inside the cover.[9] Apple's guide warns about them directly:
To use the clock/calendar, you need to install batteries. But be careful: Some types of battery cells are more prone to leak than others. Periodically check your batteries for leakage. When installing or replacing batteries, be sure you do not use carbon-zinc cells.[9]
The batteries are needed only for the clock/calendar.[9] Apple's service instructions for the Apple III clock kit specify AA alkaline cells.[6] Lift the cover and check the clip for leakage before powering up a machine of unknown history. See Battery Explosion, Capacitor or Corrosion Damage for cleaning up after a leak.
The clock rate is set with a trimmer capacitor. On the III Plus it can be turned with a screwdriver through a small hole in the base plate under the keyboard, without removing the keyboard. Apple's procedure uses the Apple III Clock Calibration Program: select the 10-second interval, wait for two speaker clicks, and adjust until the displayed number reads +560 ±9 (551 to 569), then check the clock against a time signal after about 24 hours.[6]
Ports
[edit | edit source]The back panel matches the Apple III's. It has two DB-25 connectors that are not interchangeable: one is the RS-232-C serial port, the other the disk port for up to three daisy-chained Disk III drives.[3] There are two DB-9 joystick connectors, the first shared with the Silentype III printer, an RCA socket for black-and-white composite video, and a DB-15 colour video connector that "supplies seven different video signals and four power supply voltages".[10] Four 50-pin expansion slots sit inside the case.[3]
Power supply
[edit | edit source]The owner's guide specifies a high-voltage switching supply producing +5, −5, +12 and −12 V, 100 W maximum, from 107 to 132 V at 60 Hz.[3]
Apple's parts list gives one service replacement supply, 661-71125, for both the Apple III and the III Plus. It has an 11-pin connector and needs cable 590-0118 (10-pin to 11-pin); boards with the older connector use cable 590-0017.[11] The Apple III's supply is the Astec AA11190, and Apple's 1982 Astec service package gives its full component listing (reproduced on the Apple III page).[12] That package predates the III Plus and does not mention it. Its AA11190 listing differs from the Apple II's AA11040B (four 100 µF 250 V primary capacitors against four 47 µF 250 V parts), so Apple II parts lists do not apply.[12]
Mains potential is present on the primary side. See Apple II General Maintenance for the hazards and the procedure.
Security mount
[edit | edit source]There is an unthreaded hole in the baseplate just to the left of the internal speaker, 0.25 inch in diameter and 0.15 inch deep, at the bottom of a well 0.5 inch in diameter and 1.25 inches deep. It takes a bolt for fastening the machine to a table or shelf.[9] It is easily mistaken for a missing fastener.
Service notes
[edit | edit source]Apple's Apple III/III Plus Technical Procedures covers both machines unless a section says otherwise.
| Part number | Description |
|---|---|
| 661-91122 | Apple III Plus Logic Board 5 V |
| 661-91124 | Apple III Memory Board with RAM |
| 661-71125 | Power supply, Apple III and Apple III Plus |
| 590-0118 | Cable, power supply RFI Apple III Plus (10-pin to 11-pin) |
| 661-95127 | Apple III Plus keyboard |
| 815-0719 | Keyboard cover, Apple III Plus |
| 658-7041 | Apple III Plus keycap set |
| 815-0086 | Housing, Apple III and Apple III Plus |
- Before returning a logic board for exchange, remove and keep the video interlace ROM (342-0145, location F5); exchange boards come without it.[13]
- Replacement logic boards are shipped with black foam taped underneath to protect the encoder chip. Remove it before fitting the board; leaving it in place can damage the encoder chip or the board.[13]
- The III Plus has its own dealer diagnostic diskette, "Apple III Plus Dealer Diagnostic Program" (077-0032), which tests RAM, ROM, calendar/clock, disk, keyboard, sound and video. Some screens say "Apple ///" instead of "Apple /// Plus"; Apple notes this has no significance. Run another test before the keyboard test, which can hang the system if run first. If the text vibrates on screen when the diagnostic starts, turn the interlace switch off.[14]
Power-up diagnostic messages
[edit | edit source]The III Plus tests its own hardware at power-up and shows a short message if a test fails. Apple tells owners not to use the machine after one appears, because a defective computer can erase data on the disk.[15]
| Message | Failed test |
|---|---|
| ACIA | Asynchronous Communications Interface Adapter, which runs the RS-232-C serial port |
| A/D | Analog-to-digital converter for the joysticks |
| RAM | Main memory; the pattern on the screen identifies the faulty component |
| ROM | Read-only memory |
| VIA | Versatile Interface Adapters, which control internal functions |
| ZP | Zero page test of the memory-addressing circuitry |
If the tests pass but SOS will not load, the machine beeps and shows a message in inverse video; a blank screen means the disk in the built-in drive is not a program disk.[15]
Things that are not faults
[edit | edit source]- The machine does not start a language without a disk. The 4 KB ROM holds initialisation and diagnostics only.[3]
- The RCA output is black-and-white composite only, and colour appears as a 16-level grey scale on it.[3]
- Text interlace makes some displays flicker or show garbled images. Apple says it works best with green-phosphor and other long-persistence displays, needs the monitor's vertical hold adjusted, and does not suit every program; the switch is on the left side of the case, about halfway back.[16]
- The empty hole in the baseplate next to the speaker is the security mount.[9]
Documentation
[edit | edit source]- Apple III Plus Owner's Guide: specifications, ports, clock/calendar and interlace.
- Apple III/III Plus Technical Procedures: take-apart, diagnostics, clock calibration, parts list.
- Apple Astec Power Supplies service package (1982): Apple III supply component listing.
Gallery
[edit | edit source]-
Apple III Plus with Monitor III -
Rear panel, heatsink and ports -
Apple III Plus with the cover removed
Related pages
[edit | edit source]- Apple III
- Apple III Owner's Guide
- Battery Explosion, Capacitor or Corrosion Damage
- Apple II General Maintenance
References
[edit | edit source]- ↑ Steven Weyhrich, Apple II History, Chapter 7, "The Apple IIe", apple2history.org, model timeline: Apple III September 1980 to November 1983, Apple III Plus December 1983 to April 1984.
- ↑ Apple Dealer Price Lists for Apple III, Apple II, Macintosh and Lisa, Apple Computer, Inc., 15 February 1984, hosted as Apple Dealer Price Lists February 1984 (PDF). Apple III section: A3S1256 Apple /// Plus 256K System $2,995.00; A3S0256 Apple /// 256K System (w/System Software) $2,695.00.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Apple /// Plus Owner's Guide, Apple Computer, Inc., 1982, product A3L0029, hosted as File:Apple III Plus Owners Guide.pdf. Appendix D, System Specifications, Hardware, pp. 204-205: 17.5 × 18.2 × 4.8 in, cast aluminium base with moulded plastic cover; 26 lb; 6502B with extended addressing, 2 MHz peak and 1.4 MHz average; minimum 128K of RAM; 4K of ROM for initialisation and diagnostics; power supply +5/−5/+12/−12 V, 1 A, UL/CSA approved, 100 W maximum, 107 to 132 V at 60 Hz; ambient temperature 0 to 45 °C, critical factor "the temperature at which disk case can warp"; 75-key keyboard with five special keys including DELETE; text interlace 560×384; one DB-25 disk port for up to three daisy-chained Disk III drives; RS-232-C DB-25 serial port; two DB-9 joystick connectors, the first shared with the Silentype III printer; four 50-pin expansion slots. Operating System section, p. 200: SOS supports a maximum of 512 Kbytes of RAM.
- ↑ 4.0 4.1 Apple III/III Plus Technical Procedures, Apple Computer, Inc., in Apple Service Technical Procedures: Apple II/Apple III Archived Products, part number 072-0231, hosted as File:Apple III and III Plus Technical Procedures.pdf. Section 1, Take-Apart, p. 1.15: "The clock/calendar is optional on the Apple /// but standard on the Apple/// Plus."
- ↑ 5.0 5.1 5.2 Apple III Owner's Guide, Apple Computer, Inc., 1981, hosted as File:Apple III Owners Guide 1981.pdf. Appendix E, System Specifications: 74-key keyboard with four special keys; 128K of RAM; 4K of ROM for initialisation and diagnostics; power supply rails and "UL approval pending"; ambient temperature 15 to 35 °C, critical factor "the deformation temperature of diskette cases"; three text modes and four graphics modes.
- ↑ 6.0 6.1 6.2 Apple III/III Plus Technical Procedures (see above), Section 4, Modifications, "Installing the Apple III Clock Kit", pp. 4.1-4.2 (three AA alkaline batteries in the battery pack) and "Adjusting the Apple III Clock Speed", pp. 4.5-4.7.
- ↑ Apple III/III Plus Technical Procedures (see above), Appendix A, "Keyboard and Keyswitch Identification", p. A.1.
- ↑ Apple III/III Plus Technical Procedures (see above), Section 4, "Apple III Keyboard Replacement", p. 4.11 (Aug 87).
- ↑ 9.0 9.1 9.2 9.3 9.4 Apple /// Plus Owner's Guide (see above), Chapter 2, "The Clock/Calendar Function", p. 28.
- ↑ Apple /// Plus Owner's Guide (see above), Appendix B, Input/Output Port Specifications, "The Color Video Port", p. 180.
- ↑ 11.0 11.1 Apple III/III Plus Technical Procedures (see above), Section 6, Illustrated Parts List, "Apple III and Apple III Plus – Finished-Goods Assembly", p. 6.2 (rev. Nov 85), and the November 1991 service notice at the front of the volume.
- ↑ 12.0 12.1 Apple Products Information Package - Astec Power Supplies, Apple Computer, Inc., 6 August 1982, hosted as File:Apple Astec Power Supplies Service Package 1982.pdf. Component listing for the Astec AA11190 (Apple III), pages 17 to 20.
- ↑ 13.0 13.1 Apple III/III Plus Technical Procedures (see above), Section 0, Service Notes, p. 0.4 (rev. Jul 86).
- ↑ Apple III/III Plus Technical Procedures (see above), Section 5, Apple /// Plus Diagnostics, pp. 5.1-5.3.
- ↑ 15.0 15.1 15.2 Apple /// Plus Owner's Guide (see above), Appendix A, "Diagnostic Startup Messages", pp. 160-161.
- ↑ Apple /// Plus Owner's Guide (see above), Chapter 1, "The Text Interlace Switch", p. 16, and Chapter 3, "The Video Display and Text Interlace", pp. 38-39.