Project

General

Profile

Computer peripherals in 1965

Added by Mars about 3 years ago

This does bring back memories !

I have seen these things still working at Hoogovens in the early 1980's, there were even programmers that could change programs by adding and/or reparing holes in the paper tapes ;)

And as seen in the next pic: one can - with the help of a simple Arduino and 9 phototransistors (1 clock, 8 bits) - still read these old paper tapes:

Paper tape reader with Arduino


Replies (5)

RE: Computer peripherals in 1965 - Added by jcw about 3 years ago

Neat - got a link?

RE: Computer peripherals in 1965 - Added by Mars about 3 years ago

jcw wrote:

Neat - got a link?

Oh yes, thought that the picture would contain the link, but that one was not hosted on the website itself I see...

http://www.vintage-computer.com/vcforum/entry.php?458-Reading-paper-tapes-from-scratch

With lots of other pictures and text how this was build!

RE: Computer peripherals in 1965 - Added by monsonite about 3 years ago

Hi Jean Claude,

At college (c1984), my friend and I interfaced a redundant ASR-33 to a ZX81 to use it as a printer. I remember the sheer weight of the machine with it's pedestal base - carrying it up the stairs to my friend's room. It was also quite noisy - much to the annoyance of the student who lived below him.

It was good to hear your thoughts about the PDP-8 and PiDP-8 - quite similar to my own. Many of these older machines can be emulated with quite simple hardware - I guess you don't really need a 1GHz 32bit Pi to emulate a 1MHz 12-bit PDP-8.

I love the simplicity of the whole paper tape loading method - accomplished with very simple hardware. Some PDP-8i machines had the RIM-loader instructions screen printed to the front panel (see attached) - just 16 words - and you had the means to load a tape!

These days we need UARTs, USB-serial adaptors, virtual comm ports and a whole lot of megabyte drivers just to load code into the IC. There really has to be a simpler way!

Thanks for sharing

Ken

RE: Computer peripherals in 1965 - Added by monsonite about 3 years ago

Hi JCW

In 1965 the PDP-8 cost $18,000 at a time when a VW beetle cost $1750

The attached picture sums up that era.

This site details the restoration of an original PDP-8 "Straight 8"

http://www.pdp8.net/straight8/functional_restore.shtml

Notable is the link to the Excel spreadsheet that lists all the components on all of the modules used.

If I recall rightly DTL (diode transistor logic) nand gates used n+1 diodes (cheap) per logic input for every transistor (expensive).

Diodes could produce the wired OR function without the need for additional transistors. Diodes could be arranged in a matrix to produce a simple ROM.

If you look at the schematic for the PDP-8 bitslice you see just how many diodes were used to bring in all the control signals.

For example R210 PDP-8 Accumulator has 12 transistors and 123 diodes, and the R211 - a 3 bit register slice has 13 transistors and 137 diodes.

12 accumulator/alu slices and 12 register slices were used in the PDP-8. - accounting for about 20% of its transistor count and 30% of its diode cfount.

http://dustyoldcomputers.com/pdp-common/reference/drawings/modules/r/r210.pdf

In the PDP-8 about 10000 diodes and 1400 transistors were used in the design.

Every trick in the book was used to economise the hardware - including the minimal instruction set.

Much of the circuitry in the PDP-8 was required to control the magnetic core memory.

Ken

pdp-8_VW.jpg (97.6 KB) pdp-8_VW.jpg Expensive VW!
2444

RE: Computer peripherals in 1965 - Added by jcw about 3 years ago

Hey Ken, lovely picture - so totally dated! - Let me include it inline for our other readers:

As for the complexity of our development harnesses (straightjackets?) these days... I've been rediscovering - and greatly enjoying - Forth. Its flexibility and down-to-the-metal simplicity and performance is astonishing. More about that in this week's upcoming episode.

-jcw

    (1-5/5)