Sothius' Home of Ancient Microcomputers

Siemens PC-D

Siemens logo (6 KBytes)

Siemens PC-D

Siemens PC-D (48 KBytes)

This Siemens PC-D got the newer, smaller keyboard (see below)
(picture copyright by M.A.Grundke)

Specifications

Name Siemens PC-D

Made by Siemens

Released
November 1984
this particular machine was produced in 1985, as indicated by some of the chips' production dates
the PC-X, on which the PC-D is based, was launched in 1982

Additional info Siemens PC-D/X
S26361-L17-V25
HOS: 10
Fabr.Nr. 600572

Board-info
SYBAC S26361-D359V2GS
W26361-D359-24-01-36
W26361-D359-24-01-54 C26361-D359-W100
W26361-D359-24-01-5

as Hans Franke has pointed out, this PC-D is a so-called 're-design model', with several modifications compared to the original board (such as the ability to use 256Kx1 DRAMs, or zero waitstate operation when no MMU is present)
also see the board overviews

CPU Intel R80186
the i80186 is basically the microcontroller-version of the 16 bit i8086, with an additional ALU (arithmetic logical unit) to speed up complex code, and several smaller improvements such as new instructions. It integrates timer, DMA- and interrupt-controller on-die, saving up to 25 ICs on the mainboard compared to the i8086

empty sockets to take an i8087 FPU and i82188 IBC. Compared to a standard i8086 design, an i80186/ i80188 needs the additional i82188 IBC ('integrated bus controller') to interface to an i8087 (in i8086/ i8088 systems, the i8288 bus controller is used for that purpose)

Speed 8 MHz

RAM Intel 8208 DRAM controller
512 KBytes:
18 pcs. NEC D41256C-15 (256Kx1)
makes a total of 576K RAM, but 2 pcs. NEC D41256C are used for parity
expandable to 1024 KBytes (36 pcs. 256Kx1, 4 pcs. for parity)
was also sold with 128K/ 256K (1984, earlier board) and 1024K (1985)

empty socket for a 6116-type RAM (2 KBytes), which is backed-up by the machine's battery
being Unix-machines, the PC-X and PC-MX feature an additional memory management unit (MMU) which the PC-D lacks, since it's not required

ROM/ Native OS Siemens PC-D GRAPHIK BIOS Version 4.27
as its name implies, this BIOS version was adopted to work with the graphic display controller. Of course it also contains standard BIOS functions, such as bootstrap, with the addition of a diagnostic firmware, which is called in case of error and popped up with useful debugging information (i.e. if a program crashes the OS) - nice!
the PC-D came with Siemens-specific MS-DOS 2.11 (e.g. different IO.SYS) as OS. According to Hans Franke, DOS 3.3 (with Windows 2.0) was the last officially supported DOS, but inofficially, even DOS 4.01 and DOS 5.0 existed as PC-D versions
the PC-X was running SINIX 1.x, and thus came with an additional MMU

Keyboard/ Layout 104 keys/ german (QWERTZ) layout
connected via one of the serial ports (and only works on that particular port)
this is the later keyboard (type S26381-K69-V420). The earlier version was much bigger and had multi-colored function keys

Graphics Graphic display controller on VG96 local bus
Max.Res.: 640x350/ 720x350 (monochrome)
Text: 80x25 characters, 4 attributes
not compatible to any video standard (e.g. video RAM has a different address-range than that of most IBM-compatibles, to make more contiguous DOS-memory available)
the PC-D came with a 12" CRT b/w monitor, 70 Hz refresh
when the ealiest machines were shipped in 1984, only the 'MDA-like' alphanumeric display controller was available, which couldn't produce graphics
the PC-D's display controllers were not just output devices - instead, they contained a 97801 terminal's functionality, which, depending on the model, even came with connectors for additional terminals (e.g. for multi-user SINIX)
other specialties:
the monitor gets its power from the graphic board
text output can be completetly inverted to white on black (default is black on white)
the monitor switches off the CRT automatically after a certain time to avoid burn-in damage

Sound internal, piezo-electric buzzer

Media WD2793A-AL floppy-controller
Siemens SM912 SCSI interface
SMS OMTI Model 5100 controller, ST506-interface (for up to two harddisks)
5.25" 'slimline' TEAC FD-55FV-13-U, capable of handling:
5.25" disks, 360 KB/ disk (40 tracks, standard IBM-format)
5.25" disks, 720 KB/ disk (80 tracks, unusual format, which was rarely used in other IBM-compatibles, since QD-disks (5.25", 1.2 MB) were introduced with the IBM AT. However, some CP/M systems made use of 5.25"/ 720K disks)
5.25" (half-height) ST506-interface harddisk, 13.3 MBytes capacity, type: BASF 6188
a 20 MByte harddisk was available later
a tape drive was optional, requiring a different OMTI controller (5300)

Input/ Output 2x AM26LS31PC quadruple differential line driver
AM26LS32BPC-B quadruple differential line receiver
Intel 8288 bus controller
2x Intel 8259A PIC ('Programmable Interrupt Controller')
3x Motorola MC2661PB EPCI ('Enhanced Programmable Communications Interface')
Motorola MC146818P RTC (real-time clock), backed up by a 3.5V lithium battery
3x Texas Instruments SN75154N quadruple line receiver
2x Texas Instruments SN75188N quadruple line driver
1x 9 pin SUB-D TTL monitor-out
4x 9 pin SUB-D serial port (V.11/V.24), for printers & modems (one of them used as keyboard-connector)

2x 25 pin SUB-D parallel ports
2x 34 pin internal floppy-connectors onboard
50 pin HD-controller connector (for the OMTI)
96 pin VG96 local bus for internal expansion

the machine has RESET and DEBUG-buttons; when pressing DEBUG, all active CPU-registers and flags are displayed - very useful for programmers. Also special are the two power-LEDs: during startup, an additional red LED indicates that the firmware's diagnostic routines are running

Miscellaneous
The Siemens PC-D is based on the earlier PC-X which had already appeared in 1982. It was conceived as a Unix workstation running SINIX, Siemens' Unix derivate and predecessor to Reliant UNIX. This also explains the main difference between PC-D and PC-X: the latter came with an additional MMU required for SINIX (thanks to Hans Franke for that info). Also interesting: the PC-X came with Single-User SINIX - the multi-user variant was reserved for the PC-MX series (i8086 machines which e.g. featured additional interfaces to connect terminals)

Both PC-X and PC-D shared large parts of their design with the Siemens Transdata-9781 terminals, which were essentially i80186-based workstations capable of running SINIX and MS-DOS
A PC-D running MS-DOS 2.11 (and later up to DOS 3.3) was IBM-compatible as long as no direct hardware access was done by the software. So this compatibility, as Elmar Duensser has pointed out, was often more of a theoretical nature. The PC-D's successors (PCD-2 etc.) gave up on that Siemens-specific design and were 'ordinary' IBM-compatibles

Intel's 80186 microcontroller was an enhanced i8086, with some interesting design additions (like the already mentioned ALU, or optimizations also implemented in the i80286). It was only used in very few PC-designs, such as Tandy 2000 or Philips Yes (mainly because the i80286 was already available since 1982). Notable is that there also was a microcontroller version of the i8088, the i80188
Siemens PC-D/ PC-X could also be used as workstations for the german Teletext-service
The Siemens PC-D and PC-X were in many ways advanced, compared to the IBM PC and compatibles (i80186, better IRQ handling, diagnostic functions, more continuous DOS memory available, better UARTs, VG96 local bus). But the price to pay for this was reduced compatibility and, of course, higher production cost, so Siemens dropped the PC-D series' unique design in favour of 'standard' IBM-compatibles (beginning with the PCD-2)

'SINIX' is a registered trademark of Fujitsu-Siemens. 'MS-DOS' is a registered trademark of Microsoft Corporation. All other content, including pictures is (C) M.A.Grundke (aka Sothius), unless otherwise noted. Unauthorized copying or usage of that content, without former permission from M.A.Grundke or the rightful copyright-holder, is prohibited

Sothius' Home - Museum - Miscellaneous - Siemens PC-D - additional pictures

Name	Siemens PC-D
Made by	Siemens
Released	November 1984 this particular machine was produced in 1985, as indicated by some of the chips' production dates the PC-X, on which the PC-D is based, was launched in 1982
Additional info	Siemens PC-D/X S26361-L17-V25 HOS: 10 Fabr.Nr. 600572
Board-info	SYBAC S26361-D359V2GS W26361-D359-24-01-36 W26361-D359-24-01-54 C26361-D359-W100 W26361-D359-24-01-5 as Hans Franke has pointed out, this PC-D is a so-called 're-design model', with several modifications compared to the original board (such as the ability to use 256Kx1 DRAMs, or zero waitstate operation when no MMU is present) also see the board overviews
CPU	Intel R80186 the i80186 is basically the microcontroller-version of the 16 bit i8086, with an additional ALU (arithmetic logical unit) to speed up complex code, and several smaller improvements such as new instructions. It integrates timer, DMA- and interrupt-controller on-die, saving up to 25 ICs on the mainboard compared to the i8086 empty sockets to take an i8087 FPU and i82188 IBC. Compared to a standard i8086 design, an i80186/ i80188 needs the additional i82188 IBC ('integrated bus controller') to interface to an i8087 (in i8086/ i8088 systems, the i8288 bus controller is used for that purpose)
Speed	8 MHz
RAM	Intel 8208 DRAM controller 512 KBytes: 18 pcs. NEC D41256C-15 (256Kx1) makes a total of 576K RAM, but 2 pcs. NEC D41256C are used for parity expandable to 1024 KBytes (36 pcs. 256Kx1, 4 pcs. for parity) was also sold with 128K/ 256K (1984, earlier board) and 1024K (1985) empty socket for a 6116-type RAM (2 KBytes), which is backed-up by the machine's battery being Unix-machines, the PC-X and PC-MX feature an additional memory management unit (MMU) which the PC-D lacks, since it's not required
ROM/ Native OS	Siemens PC-D GRAPHIK BIOS Version 4.27 as its name implies, this BIOS version was adopted to work with the graphic display controller. Of course it also contains standard BIOS functions, such as bootstrap, with the addition of a diagnostic firmware, which is called in case of error and popped up with useful debugging information (i.e. if a program crashes the OS) - nice! the PC-D came with Siemens-specific MS-DOS 2.11 (e.g. different IO.SYS) as OS. According to Hans Franke, DOS 3.3 (with Windows 2.0) was the last officially supported DOS, but inofficially, even DOS 4.01 and DOS 5.0 existed as PC-D versions the PC-X was running SINIX 1.x, and thus came with an additional MMU
Keyboard/ Layout	104 keys/ german (QWERTZ) layout connected via one of the serial ports (and only works on that particular port) this is the later keyboard (type S26381-K69-V420). The earlier version was much bigger and had multi-colored function keys
Graphics	Graphic display controller on VG96 local bus Max.Res.: 640x350/ 720x350 (monochrome) Text: 80x25 characters, 4 attributes not compatible to any video standard (e.g. video RAM has a different address-range than that of most IBM-compatibles, to make more contiguous DOS-memory available) the PC-D came with a 12" CRT b/w monitor, 70 Hz refresh when the ealiest machines were shipped in 1984, only the 'MDA-like' alphanumeric display controller was available, which couldn't produce graphics the PC-D's display controllers were not just output devices - instead, they contained a 97801 terminal's functionality, which, depending on the model, even came with connectors for additional terminals (e.g. for multi-user SINIX) other specialties: the monitor gets its power from the graphic board text output can be completetly inverted to white on black (default is black on white) the monitor switches off the CRT automatically after a certain time to avoid burn-in damage
Sound	internal, piezo-electric buzzer
Media	WD2793A-AL floppy-controller Siemens SM912 SCSI interface SMS OMTI Model 5100 controller, ST506-interface (for up to two harddisks) 5.25" 'slimline' TEAC FD-55FV-13-U, capable of handling: 5.25" disks, 360 KB/ disk (40 tracks, standard IBM-format) 5.25" disks, 720 KB/ disk (80 tracks, unusual format, which was rarely used in other IBM-compatibles, since QD-disks (5.25", 1.2 MB) were introduced with the IBM AT. However, some CP/M systems made use of 5.25"/ 720K disks) 5.25" (half-height) ST506-interface harddisk, 13.3 MBytes capacity, type: BASF 6188 a 20 MByte harddisk was available later a tape drive was optional, requiring a different OMTI controller (5300)
Input/ Output	2x AM26LS31PC quadruple differential line driver AM26LS32BPC-B quadruple differential line receiver Intel 8288 bus controller 2x Intel 8259A PIC ('Programmable Interrupt Controller') 3x Motorola MC2661PB EPCI ('Enhanced Programmable Communications Interface') Motorola MC146818P RTC (real-time clock), backed up by a 3.5V lithium battery 3x Texas Instruments SN75154N quadruple line receiver 2x Texas Instruments SN75188N quadruple line driver 1x 9 pin SUB-D TTL monitor-out 4x 9 pin SUB-D serial port (V.11/V.24), for printers & modems (one of them used as keyboard-connector) 2x 25 pin SUB-D parallel ports 2x 34 pin internal floppy-connectors onboard 50 pin HD-controller connector (for the OMTI) 96 pin VG96 local bus for internal expansion the machine has RESET and DEBUG-buttons; when pressing DEBUG, all active CPU-registers and flags are displayed - very useful for programmers. Also special are the two power-LEDs: during startup, an additional red LED indicates that the firmware's diagnostic routines are running
Miscellaneous	The Siemens PC-D is based on the earlier PC-X which had already appeared in 1982. It was conceived as a Unix workstation running SINIX, Siemens' Unix derivate and predecessor to Reliant UNIX. This also explains the main difference between PC-D and PC-X: the latter came with an additional MMU required for SINIX (thanks to Hans Franke for that info). Also interesting: the PC-X came with Single-User SINIX - the multi-user variant was reserved for the PC-MX series (i8086 machines which e.g. featured additional interfaces to connect terminals) Both PC-X and PC-D shared large parts of their design with the Siemens Transdata-9781 terminals, which were essentially i80186-based workstations capable of running SINIX and MS-DOS A PC-D running MS-DOS 2.11 (and later up to DOS 3.3) was IBM-compatible as long as no direct hardware access was done by the software. So this compatibility, as Elmar Duensser has pointed out, was often more of a theoretical nature. The PC-D's successors (PCD-2 etc.) gave up on that Siemens-specific design and were 'ordinary' IBM-compatibles Intel's 80186 microcontroller was an enhanced i8086, with some interesting design additions (like the already mentioned ALU, or optimizations also implemented in the i80286). It was only used in very few PC-designs, such as Tandy 2000 or Philips Yes (mainly because the i80286 was already available since 1982). Notable is that there also was a microcontroller version of the i8088, the i80188 Siemens PC-D/ PC-X could also be used as workstations for the german Teletext-service The Siemens PC-D and PC-X were in many ways advanced, compared to the IBM PC and compatibles (i80186, better IRQ handling, diagnostic functions, more continuous DOS memory available, better UARTs, VG96 local bus). But the price to pay for this was reduced compatibility and, of course, higher production cost, so Siemens dropped the PC-D series' unique design in favour of 'standard' IBM-compatibles (beginning with the PCD-2)