"Planar" is IBM-speak for what other computer manufacturers call a "motherboard". Starting from the microchannel computer systems, which introduced hardware that could be identified and configured with software, IBM (and other licenced manufacturers producing microchannel systems or planars) set a semi-unique (there are several duplicates) 16-bit "Planar ID" so that software can identify the planar it is operating on. Most, but not all, systems that have a Planar ID will have a microchannel bus (there is also the dual bus MCA/PCI Server 320/520 planar, and the dual bus EISA/PCI Server 320/520 planar, both with Planar IDs) so the CheckMCA routine normally should be run before trying to retrieve a Planar ID. The Planar ID value is gained by clearing the Most Significant Bit ("MSB") on port 94h, getting the high byte value from port 101h, then the low byte value from port 100h. Once you have retrieved the Planar ID, set the MSB for port 94h again. These routines do not incorporate any I/O port read delays and may get inconsistent or inaccurate results on some planars.
Assembly Language Routine;---------------------------------------------- ; PlanarID Assembly routine ; This routine retrieves the MCA planar ID. ; The CheckMCA routine should be run first to ; make sure it is a microchannel computer. ; Pseudocode - add dummy I/O port reads ; ; Entry: ; None ; ; Exit: ; AX = Planar ID ; ;---------------------------------------------- PlanarID proc near cli out 94h,7Fh mov DX,101h in AL,DX mov AH,AL dec DX in AL,DX out 94h,0FFh sti PlanarID endp
'---------------------------------------------- ' PlanarID BASIC function ' This function retrieves the MCA planar ID. '---------------------------------------------- FUNCTION PlanarID OUT &H94, &H7F HighByte = INP(&H101) LowByte = INP(&H100) PlanarID = (HighByte * 256) + LowByte OUT &H94, &HFF END FUNCTION
Supported Models (and Planar IDs):
Duplicates shown with an asterisk
PS/2 Model 50-021 FBFFh * PS/2 Model 50Z F9FFh * PS/2 Model N51SX F1FEh * PS/2 Model N51SLC F1FEh * PS/2 Model 53SLC2 E3FEh * PS/2 Model 55SX FBFFh * PS/2 Model 55LS F5FFh PS/2 Model 55LS 486 E3FEh * PS/2 Model 56SX (8556) E6FEh * PS/2 Model 56SLC (8556) E6FEh * PS/2 Model 56SLC2 (9556) E1FEh * PS/2 Model 56SLC3 (9556) E1FEh * PS/2 Model 57SX (8557) E2FEh * PS/2 Model 57SLC (8557) E2FEh * PS/2 Model 57SLC2 (9557) E0FEh * PS/2 Model 57SLC3 (9557) E0FEh * PS/2 Model CL57SX F1EFh * PS/2 Model 60 F7FFh * PS/2 Model 65SX E3FFh * PS/2 Model 70 386 (16MHz) DFFFh PS/2 Model 70 386 (20MHz) F3FFh PS/2 Model 70 386 (25MHz) F9FFh * PS/2 Model 70 486 (25MHz) FCFFh PS/2 Model 70 486 (33MHz) E3FFh * PS/2 Model P70 ("old" planar with two EPROMs) FFAFh PS/2 Model P70 ("new" planar with one EPROM) F4FFh PS/2 Model P75 E0FFh PS/2 Model 76 (Bermuda) DFFEh PS/2 Model 76i/s (Lacuna 25/33) EE7Bh PS/2 Model 76i/s (Lacuna 33) EE7Ch PS/2 Model 77 (Bermuda) DEFEh PS/2 Model 77i/s (Lacuna 25/33) EE79h PS/2 Model 77i/s (Lacuna 33) EE7Ah PS/2 Model 80 386 (16MHz) FEFFh * PS/2 Model 80 386 (20MHz) FDFFh * PS/2 Model 80 386 (25MHz) FFF9h PS/2 Model 80 486 E2FEh * PS/2 Model 85 (X model) FFDCh PS/2 Model 85 (K/N models) FEDFh PS/2 Model 8590 planar, any complex FF6Fh * PS/2 Model 9590 planar, any complex FF6Fh * PS/2 Model 8595 planar, any complex FF9Fh PS/2 Model 9595 planar, Type 4 complex E4FEh * PS/55 (Japanese) Model 5550-S, 5550-T FFFAh * PS/55 (Japanese) Model 5554 F1EFh * PS/55 (Japanese) Model 5571-T FFFCh ThinkPad 700 F1EEh ThinkPad 700C F1ECh ThinkPad 720 F1E8h ThinkPad 720C F1E9h 7561 Industrial PC FFFAh * 7568 Industrial PC ("Gearbox 800") FFE9h Server 310 (5 slot microchannel version) FED2h * Server 320 (PCI/MCA) FE80h * Server 320 (PCI/EISA) FEBEh * Server 500 planar, Type 4 complex E4FEh * Server 520 (PCI/MCA) FE80h * Server 520 (PCI/EISA) FEBEh * Server 720 FEE7h PC 730 (2 slot) FED0h PC 730 (6876, 3 slot) FED1h PC 750 (6886, 5 slot) FED2h * Reply 32 FEFFh * Reply 50 "Turboprocessor" E0FEh * Reply 55SX planar upgrade E3FEh * Reply 56/57/76/77 Powerboard /w Model 56 riser 0F77h Reply 56/57/76/77 Powerboard /w Model 57 riser 0F76h Reply 70 Turboboard E3FFh * Reply 80 Turboboard E2FEh * Reply 80 Powerboard 0FD5h NCR System 3220 FBFFh * NCR System 3350 F9FFh * NCR System 3421 FDFFh * NCR System 3433 F9FFh * Apricot Qi 300 F7FFh *Last modified 22 March 2022