Greenbank Electronics

MZC1

Issue: 0

Date: October 1988

MZC1


MZC-1 INTERAK HIGH PERFORMANCE CPU CARD

User Manual - Issue 0

"THE Z80280 DOSSIER"

Copyright note:

No unauthorised copies of this Manual may be made.

© 1988 Greenbank Electronics

Manual Price £5.00


XMZC-1. Interak Z80280 CPU section 1: Title pages etc.

CONTENTS

*** note, Issue 0 Manual: MANY OF THE SECTIONS BELOW MAY BE ABSENT - THEY HAVE NOT BEEN WRITTEN YET ***

							Page

1. TITLE PAGES ETC.					1-1 

	1.1 Title Page, Copyright Note			1-1 
	1.2 Preface					1-2 
	1.3 Contents					1-3 
	1.4 Errata					1-5
	1.5 Special Handling - Precautionary Notice	1-6
	1.6 Anti-static Handling Precautions		1-8
	1.7 MZC-1 General Features			1-9

2. CIRCUIT DESCRIPTION					2-1

	2.1 Introduction
	2.2 General Description
	2.3 Switch Settings, links, options
	2.4 Detailed circuit Description

3. ASSEMBLY AND TESTING					3-1

	3.1 Constructional Notes			3-1
	3.2 Setting Up and Testing			3-
	3.3 Fault Finding, Return for Service		3-

4. SOFTWARE ASPECTS

	4.1 Design of Boot ROM

5. APPENDICES						5-1

	Appendix 1: BUS Connection Description		5-A1-1
	Appendix 2: Discussion of CMOS Interface	5-A2-1
	Appendix 3: Wait state Generation		5-A3-1
	Appendix 4: Applications of MZC-1		5-A4-1
	Appendix 5: Educational Aspects			5-A5-1
	Appendix 6: General Specs for EPROM code	5-A6-1
	Appendix 7: New Data on Z80280			5-A7-1

6. DIAGRAMS AND TABLES

	(A new policy for this manual has been to 
	include a number of diagrams in the body of 
	the text where appropriate.
	They may or may not be found additionally 
	here in section 6, so we begin with a list 
	of the potentially peripatetic diagrams.)

		Comparison of Memory spaces
		Proposed Memory Map
		Proposed I/O Map
		68-pin chip Pins to Socket Translation

	6.1 Bus allocations				6-1
	6.2 Drilling and cutting Diagrams		6-
	6.3 (FUTURE). Timing Diagrams 			6-
	6.4 circuit Diagrams				6-
	6.5 Component overlay Diagram (prototype)	6-

7. PARTS LIST

	7-1 Parts List					7-1

(Total number of pages issue 0 Manual: 81)

1.4 ERRATA

Issue 0-0 October 1988

page 2-4 "expence" should be "expense"

page 2-16 wishing to (Paragraph. Forming)

page 2-17 DIAGRAMs) (bracket missing)

page 2-21 Delete critical mention of ZBUS p 2-21;

if our Z80280 catches on, then ZBUS is well worth considering, as it's made for the job. The point is that we are not going to kill the Z80 off while it still has a use.

page 3-1 Re-word: It probably does matter if socket is wrong way round

(various) page numbers need alteration; text writing and inserting etc.

1-2 "do do" should be "to do"

1-4 7-1 out of line

5-4-1 XX in front of all

p.1 XMZC-1


1.5 SPECIAL HANDLING REQUIREMENTS CMOS ETC. DEVICES.

Precautionary Notice

Some of the Integrated circuits used on this card are supplied packed in special anti-static packing (tubes, foil, or foam), and have a warning notice affixed to the packing.

Do not be alarmed, experience shows that damage due to mishandling very rarely happens.

The damage is due to static electric charges, being transferred from an object or person through the leads of the integrated circuit to the tiny chip inside. only some types of IC are vulnerable, e.g. MOS or CMOS types, and some of the latest shallow diffusion high-speed bipolar types.

The initials CMOS stand for "Complementary-Metal-Oxide Semiconductor". The oxide is, for example silicon dioxide - an excellent insulator, which insulates the metal from the silicon. (The design of the latest high speed CMOS has moved on from the metal gate type used originally, and the more correctly the internal construction of the integrated circuits is based on IGFETs: Insulated-Gate-Field-Effect-Transistors. So far as I know nobody claims to manufacture IGFET logic circuits, so I'm not going to stick my neck out and call my ICs anything but "High speed CMOS", even though the term is something akin to calling a motor car a "Petrol Engined Horse Drawn Carriage")

However the scale of IC chip manufacture is so small that whatever the construction of the internal insulating layers they are easily damaged by excessive static charges which can "punch through" an insulating layer.

Sometimes the damage is not immediately noticed (which might explain how some people disregard all precautions and appear to get away with it), but during the months and years which follow, contaminating chemical "ions" can migrate through the hole and failure can eventually result. The descriptive American term for these chips is the "walking wounded".

We would liken the risk of causing this damage to the risk of getting caught "speeding" in a motor car. Of course there are people who disregard all speed limits and never get caught, just as there are people who disregard handling precautions with no adverse effects. But do remember, every so often you meet someone who has been disqualified from driving due to being caught speeding, so do not let him handle your ICs!

The full set of handling precautions is given on the page after next; as mentioned, not everybody follows them all to the letter, but at least you cannot say you haven't been warned!


PLCC Package

This board may mark the introduction of a new IC package to some users: the PLCC (Plastic Leaded chip carrier). The CPU on the MZC-1 card is a 68-pin device, containing 140,000 transistor elements (compared with the 40,000 of the Z80A-CPU chip which we also use in the Interak system). However better things appear to come in smaller packages: the Z80A-CPU measures about 50 x 15 mm; the Z80280 is about 25 mm x 25 mm, which is a smaller area. Examination of the Z80280 (obeying the handling precautions of course) will cause the stoutest heart to sink for a moment: you will see that the connections are only 50 thousandths of an inch apart, and they are clearly intended for surface mounting techniques (where the IC is glued and soldered to the surface of the board, and if a mistake is made, or a defect shows up you not only throw the IC away you throw the whole board with it!)

Fortunately there is a socket available, with pins on normal 0.1" centres, which will accept the PLCC Ic and allow it to be used on conventional boards. It is easy to get the chip into the socket, not so easy to get it out (an expensive extractor tool is necessary; we shall probably sell these to those who want them). The socket is intended only to get users out of the jam the PLCC designers have got them into, you can see by the very small dimensions that the socket design is itself a miracle of engineering, so treat it with the respect it deserves - you do not gaily whack chips in and out every five minutes as you may have become accustomed to in your activities so far.

You will be amused to hear (when you get the bill for your expensive socket, and the expensive extraction tool) that the benefit of the PLCC package is that it is cheaper to manufacture. I'm not sure who's kidding whom, but like lambs to the slaughter, if we want to carry on playing in this field we will have to pay the price; (come back Z80 - all is forgiven!)

This is all I shall have to say about handling the PLCC chips. on the next page is the full list of standard handling precautions for CMOS etc devices (which of course apply to the Z80280 too).


1.6 HANDLING PRECAUTIONS TO AVOID DAMAGE TO VULNERABLE INTEGRATED CIRCUITS BY STATIC DISCHARGE

Before unwinding any wire shorting together the pins of the ICs, or removing the ICs from their protecting metal or antistatic carrier tube, container, or anti-static foam, please read the following precautions:

  1. Never use an isolated bit ("low leakage") soldering-iron to work on a circuit with the ICs in place. The bit should be earthed. If in any doubt, earth it by clipping on a small crocodile clip connected to earth. Similarly, all test equipment should be earthed before it is connected to a finished circuit.

  2. Work on an earthed metal plate about a few feet square, (e.g. a stainless steel kitchen sink, or cooking foil), as a work-bench, when the time comes to install the ICs.

  3. Keep all your tools on this earthed metal plate, and connect yourself to it, either by touching, or by using a piece of connecting wire formed as a wrist-strap. (Note: if you are using a wrist-strap, it is considered less hazardous to personal safety if the connection to earth is made via a 1 Megohm resistor.)

  4. Before fitting the ICs, earth your circuit board, the IC sockets, and yourself; make sure that the power supply has been turned off and all electrolytic capacitors have been completely discharged.

  5. Never leave unprotected ICs on a plastic or other nonconductive surface and never store them in ordinary white polystyrene without protection. (If a conductive tube or similar container is used, it is not possible for a damaging static potential to be built up inside such a container, nor could such a charge normally be introduced to the ICs from outside.)

  6. Damage is less likely in humid conditions than dry ones. Try to avoid nylon and similar clothing, seating and carpeting, when working with these chips.

  7. Use some form of IC sockets if you possibly can, as once the devices have been soldered, any guarantee which existed becomes void. If it is essential to solder the ICs, the supply pins should be soldered first, in order that the internal protection circuits have the maximum chance to carry out their task.


1.7 MZC-1 ADVANCED INTERAK CPU CARD FEATURES


APPENDIX 1. LIST OF ISBUS CONNECTIONS


APPENDIX 2. DISCUSSION OF CMOS INTERFACING


APPENDIX 3. WAIT STATE GENERATION

The subject of wait state generation has been covered implicitly at various appropriate stages in this Manual. The purpose of this Appendix is to make some general points on the subject, and to explain specifically why the various arrangements for wait states were made as they were.

Why have wait states?

(Space reserved for general discussion, similar to LKP-1 Manual appendix 2)

Why use a Monostable to set the wait states?

(space reserved for general discussion, similar to LKP-1 Manual Appendix 2)

Timing Diagram

(FUTURE) A detailed timing diagram is given in section _._ of this manual. It shows the various waveforms on the standard bus when an access is made to an address which triggers the wait state generation circuit on this or another card.


APPENDIX 4. APPLICATIONS

(Space reserved for general remarks similar to LKP-1 manual appendix 3)


APPENDIX 5. EDUCATIONAL ASPECTS

Although the Interak system represents a "real" computer rather than an artificial microprocessor training aid there are some distinct benefits in demonstrating various aspects of digital logic design on such a "real" computer where the student can appreciate that the theoretical techniques, such as truth tables, Boolean logic and the like have some practical application.

... ... etc. etc. (Space reserved for general discussion as in LKP-1. Manual Appendix 4)


APPENDIX 6. BOOT ROM SPECIFICATIONS

As I was talking earlier of the requirements of a new Rom to run on this card I think it is time to draw up some formal specifications.

Unfortunately lack of experience with the Z80280 in our system means that I cannot give specific guidelines yet on how the memory management should be handled by application programs, whether or not the ROM should contain any elements of an operating system and so on.

However, here is a framework on which to build:

The program should begin like this:

XX0000	Jump to program cold start
	XX0003	Jump to program warm start
	XX0004	ASCII text:

			Name of program		"XXXXXXXX.XXX." 
			Date of creation	"YY.MM.DD" 
			Version Number		".NNN"
			Latest update		"YYMMDD"
			Copyright notice	"(c)XXXXXXXX...." 
			Supplier Name/Code	"XXXXXXX." 
			Supplier Phone		"1234567890" 
			Supplier Town, Postcode	"XXXXX ..123" 
			Author Name/Code	"XXXXXX..."
			Author Phone		"1234567890"
			Author Town, Postcode	"XXXXX ..123"
			Spare			"       ...."

	XXHHH2	(a good round hexadecimal number)

			ROM Location		"0034ABCD"
			Last byte of code	"00NNNNNN"
			Last address in ROM	"12345600"
			check sum of ROM	"1234" 
			Processor type		"ZZZZ" 
			Processor speed		"0000" 
			Spare			"       ...."

	XXHHH2 (a good round number)

			Start of program Jump Tables
			Data Tables, eg lookup tables
			Text Strings used in program
			Main Program loop
			Subroutines used by Main Program
			End of Program

	Fill to end with FF bytes

Any other suggestions, comments let me know.


APPENDIX 7. LATEST Z280 INFORMATION

Zilog Z280 errata