80-Bus News


March–April 1984 · Volume 3 · Issue 2

Page 31 of 51

Gemini GM860 EPROM Programmer Review

By D. W. Parkinson

At long last the Gemini EPROM programmer is with us. At least I assume it is with us and not a holographic projection, as our Editor claimed it didn’t exist an issue or two ago! (I quote – “What EPROM programmer?” – Vol 2 Iss 5.)

What you get

i)A box 8.25″ x 4,25″ x 2″ – the programmer.
ii)A disk.
iii)A manual.
iv)A connecting cable.

What you need.

i)A disk-based MultiBoard system. (e.g. Gemini Galaxy)
ii)A mains plug.
iii)Money. (#150+VAT)

or alternatively

i)A Z80 based system with a PIO.
ii)A mains plug.
iii)The ability to program & an understanding of Z80 assembly language.
iv)Money. (#150+VAT)

What does it do?

It will program all Intel compatible single supply EPROMs from a 2716 (2kx8) to a 27256 (32kx8).

Now taking each item in turn:

The Box and cable: This is a mains powered unit containing the programmer. It has a 28-pin ZIF (Zero Insertion Force socket) sticking out of the top along with two LEDs, (one to indicate ‘power on’, the other for ‘ZIF socket powered up’). On the front is a mains on/off switch and fuse, and on the rear a mains lead emerges and there is a 34-way IDC connector. The programmer has been designed to interface to the main computer via a PIO. The interface comprises an 8-bit bi-directional bus, together with a clock line and an address line. Gemini have selected and ordered the connections such that the programmer can be plugged straight into the Centronics socket on the back of a standard Galaxy. The supplied connecting cable is just under 3″ long, with a 34-way IDC connector on one end, and a Centronics plug on the other.

Note: This does not mean that the programmer can be plugged into any Centronics type interface. On the Galaxy the Centronics socket is connected internally directly to a PIO without any intervening buffers. Thus the full bidirectional capability of the PIO’s data port is available to the control software. Similarly the Centronics “Busy” printer status line can be used as an output line in this application.

If you don’t have a Galaxy, or would rather connect the programmer direct to another PIO within the Galaxy you have two options open:

a) Make up your own cable to connect the 34-way IDC of the programmer to the usual 26-way PIO connection of the Nasom or Gemini boards. (Details are given in the documentation.)

b) Buy the internal ‘PIO-to-Centronics’ cable that is used within the Galaxy and plug the supplied cable into that. (The ‘PIO-to-Centronics’ cable is in the current Gemini catalogue at #15).

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