ICL PERQ

No, I don't have 'an' ICL PERQ. I've got 4 of them :-) I belive that PNX (PERQ Unix) was the first Unix to have graphics operations in the kernel. The first thing to do is to determine exactly what you have. There are 3 different cabinet designs, and various internal variations : PERQ 1 : The easiest way to recognise this series is that it has an 8" floppy drive mounted horizonatally on the front. On the bottom of the keyboard there's the 3 digit DDS display which shows error codes, etc. Inside the box there's a Shugart SA4000-series 14" hard disk, either 12M or (more commonly) 24M. 3 main circuit boards -- CPU, Memory (often 1Mbytes, although 2Mbytes is possible) (and video display), CIO (Just about all the input/output circuitry, including a Z80 for low speed I/O). 2 option slots for the CPU option board (never produced AFAIK), and the Optional I/O card (Ethernet, PERQlink, Laser printer controller). The monitor is a VMI portrait unit There are 2 versions of this machine : PERQ 1, with 4K of writeable control store on the CPU board and PERQ 1a with 16K WCS and some extra microinstructions. PERQ 2 : This machine has an 8" floppy drive mounted vertically on the front, and has the DDS on the main box, next to the power switch. It uses the same CPU as the PERQ 1a. The memory boards are similar, but some are modified to drive a landscape monitor. The I/O board was redesigned, and now includes an ethernet interface and more memory on the Z80 I/O processor (which can now run user-downloaded programs). Same 2 option slots, and the same Optional I/O cards work in the PERQ 2s (yes, you can have 2 ethernet interfaces on the same machine). There are 3 known versions : PERQ 2 T1 : KME Portrait monitor (normally), 8" Micropolis hard disk mounted vertically at the back of the machine. Normally 1M RAM PERQ 2T2. Normally Moniterm Landscape monitor (although a PERQ systems Portrait monitor is claimed to ezist). 5.25" ST506-interfaced hard disk. 2Mbyte machines are common. PERQ 2T4. VERY rare. It's similar to a PERQ 2T2 (5.25" drive), but the CPU is redeisgned to be a 24 bit unit. This allowed more memory to be fitted (up to 16M words == 32Mbytes), although only 4Mbyte machines are known. Changes to all 3 boards (CPU to make it 24 bit, memory to make it 4M, EIO to make the DMA controller 24 bit). Same option cards, etc. PERQ 3a (AKA PERQ AGW330). This is an ICL design (nothing really to do with PERQ systems), and uses a 68020 CPU rather than the wonderful soft-microcoded board in the older PERQs. IMHO it's a PERQ in name only (which is why the 1's and 2's are called 'classic PERQs') although the graphics processor does allow user microcode (it's a pair of AMD29116s). Looks like a deep tower PC, with a vertically mounted 5.25" floppy drive on the front, and a 4 digit hexadecimal DDS display next to it. The CPU in the classic PERQ is interesting. Most of them are 20 bit CPUs (!) using 5 74S181 ALUs. The full 20 bits are used for calculating addresses, but as the memory is only 16 bits wide, for much of the time only 16 bits are used. There are 256 20-bit wide general purpose registers. The microcode is loaded from disk[1] when the machine is powered up, so the machine can run any reasonable instruction set. There's 4K or 16K of control store controlled by an 2910 sequencer, possibly extended by 2 bits (for the 16K models) -- the '2 bit kludge' :-) [1] Yes, OK, it can also load from the PERQlink 16 bit parallel interface. 16K models also have a few extra featurs, including an 'index' register to select one of the 256 general-purpose registers (this is the only CPU I've programmed where you can do a trick like that at the microcode level), MULSTEP and DIVSTEP logic (to speed up multiplication and division), and so on. There is also a graphics processor, used to update screen bitmaps. This is part of the main CPU, and uses the latter to address words of said bitmaps in main memory. The actually graphics processor hardware combines 2 words (one from the source bitmap, one from the destination), taking account of the fact that the boundary of the region to be updated may not be a word boundary, and that the 2 bitmaps need not be bit-aligned. Oh, what the heck... Title : Raster Operations Original : Clementine Group : Traditional (?) Introduction: One of the best kept mysteries of the PERQ workstation CPU board is the operation of the 'Raster Op' machine - a circuit designed to combine two bitmaps and produce a result - obviously a useful function on a window-driven machine. Anyway, the following compuer filksong should at least partly remedy that. It's a virtually 100% accurate description of the graphics pipeline circuits and how the 2 bitmaps flow through them Song: In the wierd PERQ CPU board Released in seventy-nine Live some digital logic circuits Graphics bitmaps to combine Chorus: Raster Ops Now! Raster Ops Now! Through the shift and to combine Watch the screen image updating Through the raster op pipeline The fifo is loaded straight from memory. That's the first stage of our line. Clocked in by the controlling logic Quadwords loaded all the time. Source data flows out of the fifo To the shifter which shall align The edges of updated regions To make them easy to combine. But each word of the destination With 2 source words may combine So the last word out of the fifo is latched in the semi-pipeline Take thirty-one bits of the source words From the last stage of the line The shifter shall select just sixteen To feed on and thus combine The destination words from memory Through a single stage pipeline That's all that's needed before they enter Proms and thus with source combine The Proms take source and destination A new bitmap to combine Edges of the updated region The mask word shall now define There is one more D-type register The last stage of our pipeline To send the data back to memory Two clocks later - just in time (oooops Tine :-)) The source and destination bit fields The shift value shall define Subtracted by a control PROM Thus the 2 bitmaps align The width of the updated region With the dest we now combine This determines the edge positions And the mask we can devine A pair of small finite state machines Shall ensure this runs to time Control signals thus generating For the raster op pipeline As regards software, there are 3 common OSes : POS, which was the first (PERQ or Pascal OS). It's single-user, and uses a much modified Pascal as the system language. The POS microcode implements a modified P-code instruction set (with graphics operations, etc). PNX is PERQ Unix. Loosely System 3 IIRC. It has some kind of windowing system. Accent is a predecessor of Mach (and comes from CMU IIRC). Multitasking, and supposed to be quite reasonable to use. BUT, I use POS most of the time. Reason : It doesn't get in the way if I want to modify the microcode (something which can only be done at the 'bare metal' level). Since that's one of the main reasons for using a PERQ (if I want a unix box I've got plenty of others), I stick to POS. -tony