rhyde@ucrmath.ucr.edu (randy hyde) (04/06/91)
George, if you ever make any changes to the PC532 PCB, I have a small suggestion: It appears like "B" port on the 6250 chip is unused. I suggest that you wire up a set of 8 dip switches to this thing. That would allow owners to select certain cold boot options (e.g., system SCSI port address, initial Baud rate, whether to boot from disk or enter the monitor, whether or not an FPU is installed [shades of IBM!], etc.). Yeah, I'm already warming up the soldering iron and using some of those spare sets of holes on the board. Having a standard, supported, set of dip switches would be nice, though.
m937290@usna.NAVY.MIL (Midn. Norman R. Solis) (04/11/91)
Where can I get more information about this PC532? I've asked before but haven't received any responses. How much does it cost to build? -Rich Solis m937290@n1.usna.navy.mil -- N Richard Solis m937290@n1.usna.navy.mil GO NAVY! USNA 33rd Company m937290@midn.ecs.usna.navy.mil BEAT ARMY! Annapolis, MD 21412 (301) 267-5001 United States Naval Academy - Class of 1993
george@wombat.UUCP (George Scolaro) (04/15/91)
In article <303@usna.NAVY.MIL> m937290@usna.NAVY.MIL (Midn. Norman R. Solis) writes: > >Where can I get more information about this PC532? I've asked before but >haven't received any responses. How much does it cost to build? ^^^^ Not while I've been reading the net - must have been on holidays... Anyhow, in terms of cost to build, any of the people that have built one up should be able to tell you. Come on folks, one volunteer for the cost... FOR THOSE THAT HAVEN'T NOTICED MY PREVIOUS POSTING, A NEW PC532 PCB RUN IS PLANNED. I am getting a count for boards to run, if you want one or more please email me your name, address, quantity requested to gs@wombat.bungi.com and I'll tally the score. I have spoken to the pcb house and a run of 10 might not be outrageous in price, so far I have around 6 boards requested. With respect to what it is: ----- The PC532 is a homebrew NS32532 based motherboard. It was designed during a 2 year period, evolving from a PC/AT wirewrap prototype to a baby PC/AT sized motherboard. The complete schematics (gerber files if required) and PLD equations for the design are freely available, as is all the source code that has currently been written. The initial 'production' run of PCBs came to 65, second run of 37, and a third run of 20. With National's generous support we were able to supply 50 NS32532/NS32381/NS32202 chipsets with the first 50 PCB orders. The initial 65 boards were kitted with the more hard to get components and connectors. Kits with NS chipset were $450 and kits without were $400. The main justification for the PC532 and its brethren is to foster free hardware design and to provide a platform for development of freely available software. With the evolution of the PC/XT/AT computers, hardware hacking has been on the decline. In addition, the increasing complexity of new generation CPUs has also made it difficult for the home based tinkerer to venture into the design of a computer system. The PC532 attempts to provide the base from which new designs can gain leverage. In the long term the PC532 will likely become an adapter for a higher performance CPU. Over the past few years there has much discussion in some of the news groups about designing the ultimate homebrew computer, but this rarely ever concluded. The reality is that few people actually have enough spare time to design and carry through to completion anything other than the simplest of projects. The PC532 was architected by two people, one hardware oriented the other software oriented. Even with only two people, many discussions (battles) occurred (were fought) prior to the final specification and design. The current PC532 mailing list has a mixture of people with hardware and software backgrounds. It currently appears that the software people outnumber the hardware people. This is probably a good thing, since it ensures that any hardware that is produced will have good software support, based on the infinite number of monkeys principle (or less than infinite if some aren't monkeys :-) ). Following is a partial excerpt from the PC532 Functional Description document: The PC532 is a motherboard which mechanically fits into a PC/AT case. The mounting holes and power supply connections are arranged accordingly. The PC532 has 4 PC/XT slots which are mechanically placed to enable a PC/AT case to be used, though electrically they support the SCSI protocol. The printed circuit board (PCB) has 6 layers, comprising of two active outer layers, 2 active inner layers, 1 power layer and 1 ground layer. The PC532 board has the following features: 1 x NS32532 25 Mhz CPU 1 x NS32381 25 Mhz FPU 1 x NS32202 10 Mhz ICU 1 x DP8490 SCSI device that manages a 62 pin XT mechanically compatible 4 slot multi-master bus. This bus can run to at least 3.8 megabytes per second. Multi-master is supported by the DP8490 SCSI device. 1 x AIC6250 SCSI device, connects to a 50 pin SCSI header. This device is intended to connect to hard disk and mag tape media. The AIC6250 supports async and sync SCSI. The interface supports data transfer rates over 4 megabytes per second. 4 x SCN2681 DUARTs. This gives the PC532 8 serial channels, which are all individually connected to interrupt inputs on the ICU. Each DUART generates an INT and in addition a wire or-ed RX ready channel A/channel B. 1 x 27256 EPROM (200 ns). This EPROM contains any necessary boot firmware. It is intended that a Dallas Semiconductor (or compatible) clock chip/socket be used under the EPROM to give the PC532 a battery backed real time clock. 4/8 megabytes (1 megabit x 8/9 80ns SIMMs) or 16/32 megabytes (4 megabit x 8/9 80 ns SIMMs). Page mode dram devices must be used and the design utilizes the page mode access to achieve 0 wait state read (1st access), 0 wait state write, 1 wait state for the rest of a read burst if in page. If not in page a penalty of 4 wait states for reads and 3 wait states for writes occurs. The result is a peak 50 megabyte/second memory interface (while bursting in page). The board currently runs a modified version of MON16 which enables a 32000 host system to download code, set break points, source level debug etc. Bruce Culbertson has also ported his monitor to the PC532 and Minix. Many other people are working on different flavours of OSes etc. Compute performance is roughly 10 X a 32016 based system (ICM3216). I/O performance should be considerably faster. Total of 50 devices, including CPU etc, but excluding the DRAM SIMMs. There are 2 D-speed PAL devices and 3 B-speed PAL/GAL devices on the board. All glue logic, buffers and latches are either 74AS or 74ALS technology. The PCB is 6 layers, 13.5 inch x 8 inch baby AT form factor. It connects to a standard AT power supply (draws 2.6 Amps typical), has holes to mount in an AT chassis, has 4 XT (mechanical only) slots that will accept XT or AT wirewrap prototype cards (power pins are XT compatible). ------ P.S. I designed the hardware (with architectural help from Dave Rand), and routed the PCB. best regards, -- George Scolaro george@wombat.bungi.com [37 20 51 N / 122 03 07 W]