UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Computers

Notices

Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

Closed Thread
 
Thread Tools
Old 18th Jan 2017, 4:35 pm   #21
Guest
Guest
 
Posts: n/a
Default Re: They don't come much more Vintage than this

I dread to think just how much code is run when I merrily click my wireless USB mouse. I still use BASIC to try out formulae and generate look up tables. When selecting a microprocessor these days I go for I/O (input output) pin count to make hardware design easy, there is always much more than enough 'computer' behind it to do the job.
 
Old 18th Jan 2017, 5:02 pm   #22
bluepilot
Heptode
 
Join Date: Feb 2010
Location: Duffort, Gers, France
Posts: 713
Default Re: They don't come much more Vintage than this

Quote:
Originally Posted by merlinmaxwell View Post
I dread to think just how much code is run when I merrily click my wireless USB mouse.
It's all a question of cost. Many years ago if you wanted to add two and two it was cheap enough to pay a programmer to write a small program to do it. Nowadays it's cheaper to install a full version of Linux and use the built-in calculator.
__________________
Stuart

The golden age is always yesterday - Asa Briggs
bluepilot is offline  
Old 18th Jan 2017, 5:57 pm   #23
Guest
Guest
 
Posts: n/a
Default Re: They don't come much more Vintage than this

I wasn't thinking about cost just the sheer amount of code, probably more than I have ever written!
 
Old 18th Jan 2017, 8:24 pm   #24
Dave Moll
Dekatron
 
Dave Moll's Avatar
 
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,113
Default Re: They don't come much more Vintage than this

... and with the processing speeds that were available when I started, the run time of today's programs would probably be about on a par with the seven-and-a-half million years it took Deep Thought to calculate the ultimate answer to life, the universe and everything.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley)
Dave Moll is offline  
Old 18th Jan 2017, 9:23 pm   #25
Guest
Guest
 
Posts: n/a
Default Re: They don't come much more Vintage than this

Carrying on with the above in a slightly unfair comparison...
BBC Micro 2MHz, say 1/2 a second to boot.
Modern PC 2GHz 20 seconds to boot.
40 million times worse, so a program that would take a couple of months on a modern PC would take the 7.5 million years on a BBC micro, not too far fetched. Well done Mr Adams, and spot on Dave.

Last edited by Guest; 18th Jan 2017 at 9:24 pm. Reason: added an e and an o
 
Old 18th Jan 2017, 9:32 pm   #26
TonyDuell
Dekatron
 
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,180
Default Re: They don't come much more Vintage than this

To go back a few messages...

It's possible the 'washing machine' was a drum, although those weren't that common on PDP8 systems. There were fixed-head disks, etc, but they again tended to be just a 6U rack module.

The RK05 was available on the later (Omnibus) PDP8 machines, the PDP8/e and PDP8/a for example. The drive is the same as the drive used on PDP11s, but the disk cartridges aren't. PDP11 machines, being 16 bit, use a 12 sector cartridge, PDP8 machines (12 bit) use a 16 sector cartridge. These are hard sectored, with the sectoring determined by slots in a ring on the disk hub. 12 sector cartridges are easy to find, 16 sector ones much less so...

The original PDP11 bootstrap ROM was also a diode matrix, this time it was simply mapped into the CPU address space. There were several available, one of them could boot the RK05 and several other devices. The schematics for this board include diagrams of where the diodes go for each version. Anyway, to boot an RK05 using it you had to load the starting address of the ROM into the frontpanel address register (using the swtiches, of course) then re-set the switches to the CSR (Command/Status Register) address of the RK11 (RK05 controller) and start the processor. I realised there were a few unused locations at the end of the ROM. So I added some 1N4148s so that entering at the first normally-unused location would load the RK11 CST address into the right register and then jump to the normal bootrap code. Meaning I could leave the panel switches set to that address, then just hit Load Address and Start to boot the RK05.
TonyDuell is offline  
Old 18th Jan 2017, 9:34 pm   #27
Dave Moll
Dekatron
 
Dave Moll's Avatar
 
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,113
Default Re: They don't come much more Vintage than this

I should, however, point out that "when I started" was some years before the advent of the BBC Micro - though this was, indeed, the first computer I owned. The ones I worked on were all way way beyond my budget, even though some had less processing power than the Beeb.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley)
Dave Moll is offline  
Old 19th Jan 2017, 3:00 am   #28
Karen O
Rest in Peace
 
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
Default Re: They don't come much more Vintage than this

Wow, you were at Southampton the same time that I was, Craig!

The electronics department had an ancient computer, looked after by a very helpful guy, and having an EPROM programmer attached. I typed the 4k of hex into that machine to blow the EPROMs for my first SC/MP NIBL computer. I probably still have the paper tape somewhere.

I remember patching the binary of a program by replacing instructions with jumps to some unused memory. The patched-in code would include the overwritten instructions plus the new ones for the patch. The last thing the patch would do is jump back to the place where the original code was altered.

As for object oriented programming: people were doing that as a matter of discipline way back in the 60s. Back then, a pointer to an object (which is really just a group of variables defining the state of the object) was passed explicitly (e.g. FILE object in Unix).

It was sold as new thing by what I describe as the 'Silver bullet industry' - dozens of shady outfits selling fads to department managers. Formalising object oriented programming introduced nothing new, just error messages when someone writes sloppy code ( which of course the managers like because they think they can hire lousy programmers).

Rant over.
Karen O is offline  
Old 20th Jan 2017, 9:46 am   #29
Karen O
Rest in Peace
 
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
Default Re: They don't come much more Vintage than this

I think I got carried away in my last post to this topic. Apologies.
Here's a computer related thought to lighten things: If dogs ever make computers, do you think they might program them in Olfactory C++ ?
Karen O is offline  
Old 20th Jan 2017, 3:20 pm   #30
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,636
Default Re: They don't come much more Vintage than this

I've seen those "washing machine size" disc drives, whilst working on telecoms systems in a bank computer centre. I understood that they were about 500GB, peanuts these days but back then they would presumably have been state of the art for ultra reliable storage. If I remember correctly I had something like 40GB in my home computer.
AC/HL is offline  
Old 20th Jan 2017, 3:26 pm   #31
mole42uk
Nonode
 
mole42uk's Avatar
 
Join Date: Aug 2010
Location: Resolfen, Wales; and Bristol, England
Posts: 2,587
Default Re: They don't come much more Vintage than this

Back when I saw a PDP style 'drum' it was more likely that your home computer had a 40Mb drive, not 40GB - in those days I had a NASCOM 2 and couldn't even afford a floppy. The first hard drive I owned was an 8" 5Mb unit which I never got to work properly and the first working drive was a 20Mb 5ΒΌ" in a Mac SE.
__________________
Richard

Index:
recursive loop: see recursive loop
mole42uk is offline  
Old 20th Jan 2017, 4:42 pm   #32
AC/HL
Dekatron
 
AC/HL's Avatar
 
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,636
Default Re: They don't come much more Vintage than this

Ah yes, Mb, and I bought that as an upgrade!
AC/HL is offline  
Old 20th Jan 2017, 5:54 pm   #33
dseymo1
Retired Dormant Member
 
Join Date: Dec 2007
Location: Shropshire, UK.
Posts: 3,051
Default Re: They don't come much more Vintage than this

MB, surely?
At the time, it was generally accepted that nobody would ever need more than 40 MB in a home computer!
dseymo1 is offline  
Old 20th Jan 2017, 7:53 pm   #34
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,424
Default Re: They don't come much more Vintage than this

Attached the start up current for a removable 300MB CDC SMD disk drive. This is 208VAC single phase 60Hz but the 230VAC 50Hz was not a lot different. A row of these had to be started in sequence, internal circuits switched them on one by one. Normal run current was about 8 amps.
Happy days fixing them.
Frank
Attached Thumbnails
Click image for larger version

Name:	IMG_1151.jpg
Views:	105
Size:	30.1 KB
ID:	136194  
Nuvistor is online now  
Old 20th Jan 2017, 8:32 pm   #35
Dave Moll
Dekatron
 
Dave Moll's Avatar
 
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,113
Default Re: They don't come much more Vintage than this

Quote:
Originally Posted by AC/HL View Post
I've seen those "washing machine size" disc drives, whilst working on telecoms systems in a bank computer centre. I understood that they were about 500GB, peanuts these days but back then they would presumably have been state of the art for ultra reliable storage.
Even 500MB seems quite high capacity. I seem to remember a file limited to 2GB spread over several such top-loader washing machines when I was working on IBM 370s. I think the removable discs themselves were about 18" diameter and and about 6-8" deep. Dredging the depths of my memory seems to drag up figures of 13030 bytes per track and 20 tracks per cylinder (i.e. one track on each of 20 recording surfaces). Unfortunately, I can't remember how many cylinders there were per disc, but about 2,000 would be needed to get to the region of 500MB - and I don't recall there being that many.
__________________
Mending is better than Ending (cf Brave New World by Aldous Huxley)

Last edited by Dave Moll; 20th Jan 2017 at 8:34 pm. Reason: Noticed that GB had already been amended to MB.
Dave Moll is offline  
Old 21st Jan 2017, 1:17 am   #36
McMurdo
Dekatron
 
McMurdo's Avatar
 
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,263
Default Re: They don't come much more Vintage than this

Our Systime PDP clone at college had something like an RP04 disc pack drive, similar to this. It was just like an american washer. (92mb)
Attached Thumbnails
Click image for larger version

Name:	rp04.jpg
Views:	128
Size:	17.4 KB
ID:	136211  
__________________
Kevin
McMurdo is offline  
Old 21st Jan 2017, 11:31 am   #37
JohnBHanson
Heptode
 
Join Date: Aug 2009
Location: Worthing, Sussex, UK.
Posts: 659
Default Re: They don't come much more Vintage than this

The RK05 was for both PDP-11 and PDP-8. However beware the cartridges are different. They are hard sectored and the sector size is different between PDP-8 and PDP-11.
JohnBHanson is offline  
Old 21st Jan 2017, 3:32 pm   #38
Guest
Guest
 
Posts: n/a
Default Re: They don't come much more Vintage than this

Programming the ACE must have been fun as it used delay lines, sorting the instructions to allow for fastest execution so the next instruction arrives just after the computation has been done must have been a nightmare.
 
Old 22nd Jan 2017, 3:24 pm   #39
mole42uk
Nonode
 
mole42uk's Avatar
 
Join Date: Aug 2010
Location: Resolfen, Wales; and Bristol, England
Posts: 2,587
Default Re: They don't come much more Vintage than this

Nightmare? I'd have said "challenge"
__________________
Richard

Index:
recursive loop: see recursive loop
mole42uk is offline  
Old 10th Feb 2017, 9:55 pm   #40
AndrewScarr
Retired Dormant Member
 
Join Date: Dec 2016
Location: Morecambe, Lancashire, UK.
Posts: 20
Default Re: They don't come much more Vintage than this

Quote:
Originally Posted by merlinmaxwell View Post
My very first programme was written in Cecil https://en.wikipedia.org/wiki/CESIL running over a teletype link via a (very slow) modem to an IBM 360 in Cambridge. Such joy when it worked!
My first program was also in CECIL, written at school on coding sheets. We had to wait a week before getting our results back. It meant I became quite disciplined in my thinking.

Later we used Marked Sensed Punched cards. These were blank 80 column punched cards which we marked with a pencil, and which would then be automatically punched, before the operator would load and run them. Again we got the results back a week later, together with the cards.

I am still using a paper tape emulator at work, with the storage being on 3.5" disks.
AndrewScarr is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 10:49 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.