P112 question - what can you run that uses 1MB of RAM?

Such thigs were made for a variety of computer systems. I certainly saw one on an Acorn Archimedes. Grumpy Old Fred mentioned ISA carts to drive one. The PERQ laser printer interface was like this too (it used the PERQ praserop machine to help generate the page data). I would not be suprised if there wasn't such a printer for Suns. The interface was often called either 'direct engien interface' or 'video interface'. The de facto standard was that of the Canon CX engine. The 'DC controlelr board' (the board that cotnains a microcontroller and a gate array to cotnrol the laser power, motors, etc) in the CX pritner has a 34 pin header conenctr of the input form the formatter board. The CX-VDO model simply conencts this to the external DC37 conenctor, there is no formatter board in the printer. It's been some years since I repaired a CX pritner, turned it into a CX-VDO, and got the PERQ interfce workign. But I can still rememebr some of it. Basically, the itnerface consists of a series of low-ish speed TTL signals and a couple of differnetial ones, essentialy at RS422 levels (the drivers and receivers are 26LS31s and 26LS32s IIRC). The print sequence is soemthing like : Assert a signal to the pritner to tell it to start a page. This will get the motors turning, get the scanenr up to speed, and turn the laser on apprppraitely so that a beam detect (synchronisation) pulse is produced for each scan line. A piece of paper is then picked up and fed as far as the registraion shutter. At this point the pritner asserts a synchronisation signal abck to the host computer to say that it's done this. The host then asserts a signal to say 'start a page'. The registration shutter opens, the paper is fed towards the drum. Note that if you don';t do this in time, the printer shuts down with a paper jam error. Now the host watches the 'Beam detect' signal, one of the differential pairs. You get a pulse there for every scan line. The laster is automatically tuend on at about the appropriate time, and as the beam is deflected off the rotating polygonal mirror onto sensor, you get this pulse) The host drives the other differential pair to turn the laser on and off during each scan line. This is how it prodcues a pattern of dots on the page. Note that once you've strted a page you have to keep on sendign data until the page is complete. You can't pause it. I seem to rememebr therrs a clock and a couple of data liens for a serial interfae to the engine control microprocessor. THis lets you do thigns like select the single sheet feed, monitor the printer status (check for erors, like paper jamp), etc. But I never had to bothter with that. -tony