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Author Topic: Q&A with Bruce Tanner (IS-BASIC writer) (Read 334152 times)

Offline Zozosoft

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #255 on: 2013.April.14. 17:48:22 »
Quote from: BruceTanner
The "soft" and "hard" reset also came from Robert Madge
This is one of the best unique features of the Enterprise!
It is need some hw support: the reset button not simply connect the Reset line to GND as other machines. Reset circuit use a capacitor for the Dave which are generate the Reset impulse.

The TVC Reset works same way. Is exist any other computer which have this feature?

Offline BruceTanner

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #256 on: 2013.April.14. 18:04:24 »
Quote from: Zozosoft
This is one of the best unique features of the Enterprise!
It is need some hw support: the reset button not simply connect the Reset line to GND as other machines. Reset circuit use a capacitor for the Dave which are generate the Reset impulse.

The TVC Reset works same way. Is exist any other computer which have this feature?
I agree - one of the best features, and no I have never seen this on another computer! I cannot recall the hardware - is the capacitor just to debounce (stop glitches from) the switch? If there were any bounces, it would be the same as two resets in quick succession!

Offline Zozosoft

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #257 on: 2013.April.14. 18:18:16 »
Quote from: BruceTanner
I cannot recall the hardware - is the capacitor just to debounce (stop glitches from) the switch? If there were any bounces, it would be the same as two resets in quick succession!
At this page the Reset circuit, the switch only control the Dave RSTI input pin, the capacitor connected to the Dave CAP pin. Unfortunatelly no Dave inside schematics  :cry:

Offline BruceTanner

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #258 on: 2013.April.14. 18:39:46 »
Quote from: Zozosoft
At this page the Reset circuit, the switch only control the Dave RSTI input pin, the capacitor connected to the Dave CAP pin. Unfortunatelly no Dave inside schematics  :cry:
It says here, "A Z80 is reset provided on RSTO, either on switch­on by an external RC network on CAP, or a low going signal onRSTI. The latter generates a 1mS reset pulse synchronised to the falling edge of M1 to prevent loss of data stored in dynamic RAM".


So the capacitor (and resistor)  is to provide a power-on reset pulse (which I have seen in other designs), but there is also special support inside Dave (to make sure RAM contents survive a reset).

Offline Zozosoft

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #259 on: 2013.April.14. 19:13:40 »
About the Dave some interesting thing:
The 1983 version of document talking about 4 memory select output:
ROM,CART,XRAM,VRAM
It is great simmetry: 00-03,04-07,F8-FB,FC-FF segments decoded.
But in later documents, and in the real Dave chips only 3 memory select, the XRAM are missing.
Why removed?
Because this the EP128 production cost will be higher because address decoding chips needed to RAM expansion board.

Offline BruceTanner

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #260 on: 2013.April.14. 19:21:04 »
Quote from: Zozosoft
Why removed?
Because this the EP128 production cost will be higher because address decoding chips needed to RAM expansion board.
Well spotted...I don't know the answer, but possibly bug/problem in the Dave chip?

Offline Zozosoft

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #261 on: 2013.April.14. 19:50:36 »
Another interesting question about the Dave&memory: why added the wait state generation? (For the general memory, the Nick&VRAM are other thing)
Very strange the EXOS set 1 ws for every instruction cycle!
Why good idea slowing down the machine? Especially with the IS-BASIC, which is very good but not too fast... it is need every power of the CPU.

Probably it is for the wired prototypes? And forgot remove on the final machine?

Many-many programs start with OUT 191,12 which is disable wait states :-)

Offline BruceTanner

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #262 on: 2013.April.14. 19:57:16 »
Quote from: Zozosoft
Another interesting question about the Dave&memory: why added the wait state generation?

Probably it is for the wired prototypes? And forgot remove on the final machine?

Again I don't know the answer, but you may well be right. Or because of initial batch of "problem" Nicks!

Offline Zozosoft

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #263 on: 2013.April.24. 23:07:39 »
In other topic we talking about the Function key labels.

Bruce! Can you remember where come from the idea of the programable functions keys? And the label holder?
Another system have same function keys at that time?

Today high end keyboards have same function! :-) (Called as macro keys)

I think this is one of the little but great ideas of the Enterprise!

Offline BruceTanner

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #264 on: 2013.April.24. 23:27:16 »
Quote from: Zozosoft
In other topic we talking about the Function key labels.

Bruce! Can you remember where come from the idea of the programable functions keys? And the label holder?
Another system have same function keys at that time?

Today high end keyboards have same function! :-) (Called as macro keys)

I think this is one of the little but great ideas of the Enterprise!
When I started work on the Enterprise the shape, keyboard and joystick had already been decided - the plastics were  way ahead of the software and electronics! Maybe it was driven by requirements of the financial backers - I don't know. Other keyboards on bigger systems at the time had function keys (most notably the original IBM PC of course). I don't know of any other computer that has the labels though, but I don't know where the idea came from.

I always thought a little LCD display built into the function key tops would be nice!

Offline szipucsu

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #265 on: 2013.April.24. 23:41:46 »
Quote from: BruceTanner
I always thought a little LCD display built into the function key tops would be nice!
What an interesting idea! :D And, after typing a SET FKEY (number) BASIC command, the display would change at once. This display could have been used by certain programs, just to inform the user about anything.
100 SOUND SOURCE 2,STYLE 128,PITCH 25.2,SYNC 1
110 SOUND PITCH 25,SYNC 1
120 ! Videos

Offline Zozosoft

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #266 on: 2013.April.24. 23:59:48 »
Quote from: BruceTanner
Other keyboards on bigger systems at the time had function keys (most notably the original IBM PC of course).
Yes, but on another system the fkeys have a fixed control code, which can be detected by user softwares.
On the Enterprise the fkeys (in normal and Shifted mode) can be defined by the user, for simulating pressing any other keys.
For example type START and pressing the Enter.

Nowadays this function is called Keyboard Macros.
I think this is unique at the Enterprise time.

I wrote a utility for Function Keys, it can record key pressing for the definition, and is able to save and load Function Key settings. It can be used in any software which uses EXOS Keyboard device and can run EXOS commands.
For example I used it in Assembler, the most used subroutine calls definition to Function keys.
« Last Edit: 2013.April.25. 00:27:55 by szipucsu »

Offline lgb

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #267 on: 2013.April.25. 00:15:53 »
Quote from: Zozosoft
At todays this function called as Keyboard Macros.
I think this is unique at the Enterprise time.

Dunno about the order in time, but eg Commodore+4 has similar things, you can define something with the KEY basic command for the function keys.

Offline BruceTanner

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #268 on: 2013.April.25. 00:48:54 »
Quote from: lgb
Dunno about the order in time, but eg Commodore+4 has similar things, you can define something with the KEY basic command for the function keys.
The BBC micro had programmable function keys too I've just realised.

Offline Zozosoft

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Re: Q&A with Bruce Tanner (IS-BASIC writer)
« Reply #269 on: 2013.June.19. 11:55:41 »
Prototype TVC Sprite module
The page say it is developed in UK. And planned the final version with custom IC-s, but this is never happened.
Bruce, do you know anything about it?

The wired Enterprise prototypes looked similar?