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yet another PDP-11 barebone hack

sam2000 said:
Thanks, interesting material. As for the fpu, first of all I need to understand the benefits of having one (I think the DCJ is supporting emulated instructions) and the hardware feasibility (i.e. as of today I don't have datasheets and documentations on how to wire it to the cpu). If I manage, I could provide an empty socket for the fpu and some jumpers to enable it or not, and think about getting one when I have the money, surely you know it's not a few cents.
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Perhaps we can find a way to combine J11 with a floating-point coprocessor by integrating an FPGA on a PCB and writing a floating-point module ourselves
 
alphaaxp said:
Perhaps we can find a way to combine J11 with a floating-point coprocessor by integrating an FPGA on a PCB and writing a floating-point module ourselves
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I have no experience of FPGA, I think I can learn and manage some basic address decoding and glue logic in it, but recreating a working FPJ11, no way Jose. On the other hand, if you have the skills and the way to do it, it'll be very interesting, also because the FPJ11 is scarcely available and expensive as hell. I think initially I'll provide just an empty DIP40 socket laid out with the proper signals for the FPJ11 plus a jumper (or eventually more than one) for enabling or not the fpu.
 
Seems similar to my
sam2000 said:
Hello, inspired by other members I'm opening this new thread hoping one day to have my own self-made PDP-11.
There are many reasons that brought me to creating a PDP11 but I would be honest in saying it's for fun, for the sake of it, for giving a tribute to the PDP11, and last but not least to learn something new, to face a new challenge, to improve myself.
It's still very much a work in progress, but I can begin to lay down what I am aiming. I am open to suggestions.

Once completed the system should be able to run BSD2.11 and look "like" a 11/70 using a PiDP11 console.
I'll favor through hole components, but if neede I'll go also the SMD way. I think I'll use a modified ECB N8VEM backplane, easily available with 16bit databus and 24bit address bus. I heard the 96 pin connectors are quite costly though. For what is possible I don't want to emulate QBUS or UniBUS. Right now I have in mind a system with 4 cards.

CPU card: CPU is going to be a DCJ11, it's quite compact, powerful, easy to find, and most important I already have one.
I am unsure about the FPU, the FPJ11 21-21858 is quite rare, quite expensive, and I couldn't find its datasheet, pinout and information about connecting it to the CPU.
The memory will be 4MB of static RAM, zero wait state. I guess 50-60ns will be enough?
A CPU governor, clock generator, TOY RTC, console serial port and the necessary glue logic.

I/O card: 4 serial ports DLV11-style, and possibly some parallel ports

HD card: emulated HD to either an SD card or an IDE port

Network card: 10BASE5 AUI port

Well now for the things I still need to figure out...
I still need to figure out the correct memory map, for the serial devices and not only. Interrupt mangaement in regarding to I/O. Also the ROM is an important factor, the system should be able to boot from the HD.
I/O will have to be as close as possible compatible with DEC devices, I don't plan and don't want to get entangled with writing kernel device drivers. Out of the various PDP/HACKs available I found very interesting the minimal proof of concept of Brent Hilpert, so instead of the DC319 I think I'll use the 6402. HD emulator, other PDP hacks succeded, so it is feasible, I'll have to study on it. The network approach is more complicated, I couldn't find a working hack yet, but it's very desirable: I don't want to do networking with a 9600 baud slip.
Lastly, some logic will be needed to interface the bus to the multiplexed lights and keys of the PiDP11 console. Also, it looks to me the PiDP11 case is quite shallow, some carpenter's hack will be needed there too :)

that's it for the moment, thanks for your patience

Paolo
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Seems to match my goals that led to my PDP-11/Hack computer. FPJ11 is not really necessary as it only increases the speed of floating point instructions, but the DCJ11 already supports them in its microcode. Have a look at my home page. Feel free to ask questions.
 
cbscpe said:
Seems similar to my

Seems to match my goals that led to my PDP-11/Hack computer. FPJ11 is not really necessary as it only increases the speed of floating point instructions, but the DCJ11 already supports them in its microcode. Have a look at my home page. Feel free to ask questions.
Click to expand...
To be honest www.5volts.ch was one of my inspiring points ;-)
 
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