| Name | IBM 5150 (commonly referred to as 'IBM PC') |
| Codenames | 'Acorn', 'Chess' |
| Made by | International Business Machines (IBM) |
| Released | - August 12, 1981
- this machine was built in 1985, according to some of the chips' production dates
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| Serial-No. | 5150 *AA550192434 * |
| Additional info | Made in Greenock
Scotland
United Kingdom
Model No.5150
COPYRIGHTED CODE CONTAINED HEREIN
© COPYRIGHT 1981 IBM Corp. |
| Board-info | |
| CPU | Intel 8088- the i8088 is basically a i8086, stripped down to an external 8 bit data bus, while internally processing at 16 bit (i8086: full 16 bit operation). It was intended as a cheap alternative to its bigger brother, with the ability to be integrated in existing 8 bit designs (e.g. i8085). Both have a 20 bit address bus for a maxium of 1 MByte RAM
- this particular machine was upgraded with a NEC V20 (fully i8088-compatible but 5-10% faster)
- empty socket for i8087 floating-point unit. If an i8087 is present, it acts as a second CPU, with equal access to memory and I/O-signals.
This is accomplished by setting the i8088 into the so-called MAXIMUM mode: while normally controlling memory- and I/O-lines itself (MIN mode), the signals are then redirected to the 8288 bus controller. Now the 8288 can assign control of these lines either to CPU or FPU
- additional Zilog Z80A on its HD controller
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| Speed | 4.772727 MHz- the i8088 was originally designed for a maximum speed of 5 MHz. Later, however, Intel introduced the i8088-2 which was, in some designs, clocked with up to 9.54 MHz (e.g. Commodore PC10-III/ PC20-III/ COLT)
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| RAM | - 256 KBytes in 36 pcs. 64Kx1:
- 9 pcs. inmos IMS2600P (bank 0, soldered)
- 18 pcs. NEC D4164C (bank 1 & 2, socketed)
- 9 pcs. MOSTEK 4564N (bank 3, socketed)
- each bank uses one piece 64Kx1 for parity bits
- expandable to 640 KB (via 384 KB expansion-board)
- the earlier 16KB-64KB CPU-board had a maximum of 64 KB onboard. The second revision board (used in this machine) was introduced in April 1983, and allowed 256 KB onboard (using 64Kx1 DRAMs)
- BIOS revisions before 1982 were, due to a bug, only capable of addressing 544 KB
- the very first 5150 (5150-001) came with only 16 KB RAM!
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| ROM/ Native OS | 1983 IBM-PC BIOS (1x 8 KB ROM)
Microsoft BASIC-80 (or 'BASICA', 4x 8 KB ROM)
empty socket (for an option ROM?)- was sold with IBM Personal Computer DOS ('PC-DOS'), an IBM-licensed MS-DOS (see misc)
- if no bootable media is found during startup, the 5150 calls Microsoft's BASIC interpreter (which was also called 'cassette BASIC' or 'BASICA')
- there were three different BIOS revisions in the IBM 5150's lifespan. The first two (both dated 1981 internally) couldn't access RAM above 544 KB and expansion board's ROMs in a certain address range. The third and last revision (dated October 27, 1982) solved these problems
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| Keyboard/ Layout | 83 keys/ german (QWERTZ) layout- this one's got a third-party replacement keyboard
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| Graphics | IBM 1501985 430 V0011 'Monochrome Display Adaptor'- Text: 80x25 characters, 4 attributes
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| Sound | integrated speaker |
| Media | IBM 1501492 ST506/ST412 harddisk controller
IBM 6181682-987-V9116 floppydisk controller- 5.25" disks, 320 KBytes/ disk (double sided)
- early machines came with single-sided drives (160 KB/ disk)
- 5.25" full height ST412 MFM-harddisk, 13 MBytes capacity
- there was no 5150-model that came with harddisk by default, so this one here must have been upgraded. This upgrade must have also included
the 130W powersupply (IBM P/N 1501438), since the original 63.5 PSU wasn't powerful enough to support a harddisk. The later 5160 PC/XT, however, was also available with harddisk pre-equipped
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| Input/ Output | ľNEC PB8284AD clock generator
AMD D8288 bus controller
NEC D8237AC-5 DMA controller
AMD P8255A-5 'Programmable Peripheral Interface'
AMD P8253-5 'Programmable Interval Timer'
Intel 8259AP 'Programmable Interrupt Controller'- 9 pin SUB-D TTL monitor-out (on MDA-adaptor)
- 25 pin SUB-D parallel (on MDA-adaptor)
- 5 pin DIN keyboard-connector
- 5 pin DIN cassette-drive interface (2 KB/s)
- 37 pin SUB-D external diskdrive (on FD-controller)
- 5 expansion slots (8 bit ISA)
- standard female receptable for the integrated 130W PSU
- additional male power receptacle for a monitor ('AUXILIARY POWER TO 5151')
- machine has no battery backed-up clock - it was available as option
- an 'IBM PC expansion unit' (IBM 5161) was also available, which came in an identical case. It added two drive bays (e.g. for harddisks), 8 additional slots and its own powersupply, and was connected by placing an 'extender card' in one of the 5150's slots. The extender was connected to a 'receiver card' in the 5161 (occupying one of its slots) via a 62 pin SUB-D cable.
Must have been an impressive setup with two of these cases :-)
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| Miscellaneous | - The IBM 5150 was built around Intel's 8088, an 8/16 bit CPU - internally processing at 16 bit, while retaining 8 bit I/O for the easier integration in existing 8 bit designs. I assume that this was the main reason for IBM not to take the i8088's 16 bit predecessor, the i8086 - IBM had already built several 8 bit designs, e.g. with Intel 8085 CPU, so some parts and specifications could easily be adopted for the new 5150.
These predecessors mentioned include
- the 5100-series (including IBM 5100, 5110 and 5120, based on PALM CPU)
- the IBM 5520 Administrative System
- the IBM System/23 Datamaster (i8085-based, getting closest to the 5150)
For interesting infos and pictures on these early machines visit IBM's historic exhibition! - Successors to the IBM PC 5150 were
- IBM 5160 PC/XT (March 8, 1983): 'eXtended technology' with more slots, better power-supply and without cassette-port
- IBM 4860 PCjr (November 1983): the first try for a cheap consumer-PC (with cassette-port again!) and a total failure
- IBM 5155 Portable PC (February 29, 1984): with integrated monochrome-monitor, diskdrives and carrying handle - like many early 'portables', it was a heavy beast
- IBM 5170 AT (August 14, 1984): 'advanced technology' with 1.2 MB drives, 16/24 bit Intel 80286 CPU and 16 bit I/O (requiring many changes in design)
- IBM 5140 Convertible (April 2, 1986)
- IBM 5162 XT/286 (September 26, 1986): an AT-machine in XT-case
- IBM PS/2-series introduced (April 2, 1987): introducing MCGA-graphics, 3.5" disks and Microchannel-architecture
- IBM created the 'Industrial Standard Architecture' (ISA) with this machine, although it was not yet named that way when the 5150 appeared (it was officially introduced with the AT 5170 in 1984). However, expansion slots were nothing new - Apple had already implemented them in their 1977 Apple ][-design
- First it was planned to sell CP/M with the 5150, which was the most promising standard these days. But its' creator Gary Kildall (Digital Research) was on holidays when IBM tried to meet him to discuss necessary modifications. Irony of fate, since as a consequence, IBM decided to license Microsoft-DOS (originally created by Tim Paterson as QDOS, then aquired by Bill Gates and renamed to MS-DOS)
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