Re: Building a BA08 for a pdp8/L

[Chris Zach via cctalk]

Hi Paul!

That is really interesting. Did you need to recreate the delay lines or 
any of that circuitry, or was it just wire the NAND gates into the chip 
address matrix and ignore all the various TP1-TP4 states?


Looking at it I could probably build the basic circuitry on a large 
breadboard, I've certainly got the chips from fixing all those M series 
boards. That plus a pair of 32k*8 static ram chips from my 386 cache 
days and I should be set


Now where did that big breadboard go?

CZ

On 1/20/2022 3:51 AM, pbir...@gmail.com wrote:

Not a direct answer Chris, but back in the mid-70's I built a BM8 surrogate the hard 
way (we were an impoverished neurophysiology lab so cutting corners wherever 
reasonable) using banks of 2102L and S100 RAM PCBs.  For density I piggy-backed the 
2102's to get 8Kbyte boards, then 3 boards gave 16Kword, so 6 RAM boards were 
sufficient to fill out the memory space.  The controller was a 1:1 implementation of 
the DEC schematic, which (if memory serves) just fit onto a single S100 prototyping 
board.  Cabling from the 8/L was simple ribbon with alternating grounds.  Chassis 
was ad hoc using a S100 backplane suitably reinterpreted plus a pair of 8" 
fans. Added suitable additional DF/IF switches and lamps to the existing 
filler-panel and then attached that to the chassis-front so that it all looked 
pretty good.  It worked for many years without incident, although AFAIK only core 
memory was used for execution; the SRAM was used only for data -- and every added 
word was taken advantage of :-}.

So there's an existence proof that what you propose isn't unreasonable.  I'd 
probably have preferred to have a nice backplane and applicable modules to WW, 
but point-to-point wiring on the prototyping board worked.  Given my skill-set 
at the time it was a rather risky venture, but the ROI was excellent.  
Evidently the DEC design was forgiving enough that my recreation worked on the 
first try.

If you decide to pursue the FPGA (or something) approach I'd be interested in 
doing the same with my current 8/L.  If you go that route, might as well build 
out all three bits of DF/IF control even if there may not be any accompanying 
front-panel.

-Original Message-
From: cctalk  On Behalf Of Chris Zach via cctalk
Sent: Wednesday, January 19, 2022 11:08 PM
To: CCTalk mailing list 
Subject: Building a BA08 for a pdp8/L

So now that my pdp8/L is up and running (it now has a serial port and runs 
FOCAL69 quite well) I'm thinking about the next step, which is of course more 
memory.

This requires a BA08 or BM8/L or something expansion box but to be honest I 
have enough spare flip chips and such from the wrecked 8/I to build about 3 
core memory systems. So given that the schematics for the
BA08 are online, they look pretty darn simple, I have the parts, and I have the 
parts does anyone know if it's possible to get a flip chip backplane to work on 
and wire up to emulate a BA08?

It looks like they just used the data break interface lines to hook up to the 
processor. Everything's there, Memory address bus, memory data bus, and the 
various signals for jumps and the like that could allow one to decode and 
implement the extra instructions needed.

Hm. Might just be easier to build it with an FPGA or something as it's mostly 
linking up simple gates and the whole core memory section could be removed by a 
4k*12 memory array. Anyone ever done this?

C

Re: DEC RX01 Parts

[Mike Katz via cctalk]

Thank you.  That is what I figured.  Now all I need is a RK8E or RX28 
controller and I'm all set.


I'm becoming more and more tempted to have some of Roland's TTL version 
boards made and build one up myself.


I am trying to get an 8" shugart type drive and using the GreaseWeazel I 
will be able to format disks for RX01.


The author of the original firmware is working with me to modify the 
firmware for the screwy RX02 format.


The nice thing about the RX01 drive set that I have is that I can just 
flip a dip switch and have an RX02 instead (as long as I install the 
appropriate RX02 OS/8 driver and have the RX28 controller card).


Thanks again,

    Mike

On 1/21/2022 6:26 PM, Charles Dickman wrote:


On Fri, Jan 7, 2022 at 7:41 PM Mike Katz via cctalk 
 wrote:



I don't know if the circuit boards are compatible with the RX8E
Controller. The Read/Write Control Board is labeled 243A and the
Floppy
Disk Control Board is labeled 245A.


What I know about the RX01/RX02 is only from poring over the manuals 
and schematics.


There is only one RX01 system. It is compatible with all the 
controllers. There may be a jumper.


I don't have any other 8" floppy systems to format the disks in.


The format is IBM 3740. So quite common in the way that 8 inch 
floppies are common.


-chuck

Re: DEC RX01 Parts

[Charles Dickman via cctalk]

On Fri, Jan 7, 2022 at 7:41 PM Mike Katz via cctalk 
wrote:

>
> I don't know if the circuit boards are compatible with the RX8E
> Controller. The Read/Write Control Board is labeled 243A and the Floppy
> Disk Control Board is labeled 245A.
>

What I know about the RX01/RX02 is only from poring over the manuals and
schematics.

There is only one RX01 system. It is compatible with all the controllers.
There may be a jumper.

I don't have any other 8" floppy systems to format the disks in.
>

The format is IBM 3740. So quite common in the way that 8 inch floppies are
common.

-chuck

RE: WARNING: Clear QIC Tape Bands

[Ali via cctalk]

> Have you tried Misumi?  The only problem I had was that you have to be
> VAT
> registered. I had a friend order for me.
> 
> https://us.misumi-ec.com/vona2/detail/223000860382/
> 
> I used the 150 mm / 6mm variety and as far as I can tell it works
> nicely. I
> have been running a tape in a Tektronix 4051 for some time and haven
> seen
> any shedding. Not daily exactly but 20 times over half a year.

I second the Misumi brand. I haven't seen any of the issues mentioned on this 
thread with those bands. Of course I am only a hobbyist so not putting them 
through any crazy paces. I mainly use them for the 5100 and 5110. They are 
significantly more expensive then the Amazon mix bag ones but may be worth it.

-Ali

Re: Tiny PDP-11/73 system for sale

[Stephen Pereira via cctalk]

I have had a couple of inquiries on my system, but no takers yet.
I just want to let folks know that it is still available.
Please read the description - that is exactly what is for sale.
Please contact me for photos.

smp
- - -
Stephen Pereira
Bedford, NH  03110
KB1SXE


> On Jan 20, 2022, at 12:25 PM, Stephen Pereira 
>  wrote:
> 
> I am in the process of thinning down my vintage computer holdings, to relieve 
> some of the burden I will leave to my heirs (hopefully not too soon!).
> 
> I have a working tiny PDP-11/73 system available for sale.  I would much 
> prefer not to have to break it down and pack it for shipping, but I will if 
> the buyer agrees to pay for the packing and shipping costs.
> 
> - - - - -
> 
> Tiny PDP-11/73 System:
> 
> H9281-BA backplane and card cage
> KDJ11-A CPU
> DLV11-J 4 port SIO
> MSV11-LK 256KB/128KW memory
> Emulex UC07 SCSI interface
> 
> Power-on Reset board from here:
> http://www.heeltoe.com/index.php?n=Pcbs.Qbus-por 
> 
> 
> SCSI-to-SD hard drive emulator with 4 drives available, RT-11 installed
> 
> MeanWell RT-125B power supply
> 
> 4.5 inch AC fan
> 
> qty 4 GlitchWorks serial cables
> 
> Spare PDP-11/23 CPU saved as a backup:
> KDF11-AB CPU
> 
> RT-11 Pocket Guide
> 
> RT-11 Mini-Reference Manual
> 
> - - - - -
> 
> I am asking $800.00 for the lot.  It cost me about that, probably more to 
> acquire it piece-by-piece and assemble it into a working system.
> 
> smp
> - - -
> Stephen Pereira
> Bedford, NH  03110
> KB1SXE
> 
> 

Re: WARNING: Clear QIC Tape Bands

[Mattis Lind via cctalk]

>
> Well, both the SF-7000 as well as the SF-6500 (the size for QIC
> cartridges) are de facto unavailable/out of stock/whatever.
> The only alternative that I could find are the Mobilon Bands from
> Nisshinbo. But same story, I can't order them, there is no store that I
> could do that.
>

Have you tried Misumi?  The only problem I had was that you have to be VAT
registered. I had a friend order for me.

https://us.misumi-ec.com/vona2/detail/223000860382/

I used the 150 mm / 6mm variety and as far as I can tell it works nicely. I
have been running a tape in a Tektronix 4051 for some time and haven seen
any shedding. Not daily exactly but 20 times over half a year.

/Mattis


> Christian
>

Re: WARNING: Clear QIC Tape Bands

[Christian Corti via cctalk]

On Thu, 20 Jan 2022, it was written
On Jan 20, 2022, at 00:23, Christian Corti via cctech 
 wrote: What bands did you use/buy? I ask 
because the Baumgartens Plastibands aren't available in the required 
size (as if they are not produced any more).
I bought the assorted sizes pack (SF-7000, I think). Each pack had maybe 
10 of the green ones I use in QIC tape carts, so I bought multiple packs 
and put the rest of the bands into household use.


Well, both the SF-7000 as well as the SF-6500 (the size for QIC 
cartridges) are de facto unavailable/out of stock/whatever.
The only alternative that I could find are the Mobilon Bands from 
Nisshinbo. But same story, I can't order them, there is no store that I 
could do that.


Christian