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I remember comparing 33 MHz 386DX and 486DX systems running UNIX (so both were running identical 32 bit code) and the 486 took half the time to compile the 50K or so lines of C that I was working with. That was as real world a comparison as I needed.

Now that you fixed the broken grant chain the boot firmware can tell that the disk controller can issue IRQs and perform DMA in/out of RAM (part of the MSCP protocol). So it actually tries to boot instead of giving up because the controller didn't respond. If you had an XXDP floppy then you...

M8639 is probably an RQDX1 (could it be an RQDX2?). You need XXDP diagnostics system on RX50 diskettes so you can try to boot them. I know where to find XXDP, but how do you get it onto RX50 media so you can boot it? As far as I know all BA23 boxen came with the same backplane (first 3 slots...

I bought a fully populated PB16H rack on ebay for cheap (in 2009?), and made a cable to run from the 50-pin header to a DB25, wired to suit the PC LPT port. I ran +5V and ground from one of the Molex connectors inside the PC to power the rack. The FreeBSD PPI driver allows access to the status...

You could do that. But it could iterate for quite a while. Maybe it would be better to just provide a way for the programmer to specify that short addressing should be used, and give an error during pass 2 if it won't work.

I built/maintain a system that runs an OPTO-22 interface board from the PC printer port to operate a 3 million BTU/hour boiler, circulator pumps, etc. in a greenhouse complex. Temperature and humidity sensors, as well as remote devices (e.g. unit heaters, fans, vent operators), are interfaced...

It's been a while for me, but I still have an (8-bit) WD8003 ethernet card, a packet driver, and software that will do FTP, etc. Gotek works, too.

The first assembly language I learned was for the PDP-8. Simple. Not always straightforward, but the instructions themselves were all simple. The second assembly language I learned was for the '10. The programmers manual seemed mind bogglingly complex to me at the time (which variation of...

I have one of these boards and if I recall correctly the secondary cache will only work on the lower 32MB. I think FPM will work, but not EDO. EDIT: my board is a 4044 (not a 4045), so not quite the same.

I think I last built something with a 2114 in 1983. Maybe 1984. The RAM write cycle ends when either CS- or WE- rises (whichever comes first). Data must be valid for at least the data hold time interval after that, tDH (0?). I would first run the logic analyzer asynchronously to see how a...

In my case, the employer's VAXcluster supported users all over the USA with manufacturing sites in California, Tennessee and New York. I don't know if the European subsidiary used that system or not (probably for MRP II). By the time I left the company had a frame relay network tying all the...

VAX/VMS provided the "company mainframe" for a lot of businesses. It took a while before PCs were big enough to run company-wide or departmental databases, etc. An employer of mine used a VAXcluster for many business functions, including Manufacturing Resource Planning (and probably payroll)...

No matter what your code says, the operating system is still reading 1 or more disk sectors at a time, buffering them, and delivering them to your program as you specify.

I had a half dozen of those at work back in the day (bought as off-lease refurbs). Several of them eventually suffered from the capacitor plague. If you don't mind recapping it then go for it (or maybe it has already been recapped).

This thread is now 5 years old. Thanks for trying to help, but how does a bad oscillator correct itself after Ctrl-Alt-Del, or plugging it in to a different motherboard?

What does the back of the board look like?

It has been a long time for me, probably late '80s. It would not surprise me a bit if the SYSGEN procedure only runs correctly on the boot device (which is expected to be a clean distribution kit). There may be hack-arounds for this, but not for the faint of heart. The virgin system (i.e. one...

Did you take a crash dump on MU0:? Did you look at listings/maps to find out what happened at "PC=044720 FACILITY=000311 ERROR CODE=000207"?

Yes. I don't think I have ever had one that didn't.

I knew guys at Syracuse University in the early 80s who were already finding homes for PDP-8 and PDP-12 machines that were being taken out of service in industrial and medical facilities. One of them owned a Straight-8 with 4K core and 28K semiconductor RAM (2102s on a custom board).