Sharp MZ-3500 service manual Specification of keyboard control, At rrn, Key

Models: MZ-3500

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MZ3500

10. MZ1K01 KEYBOARD CONTROLLER CIRCUIT DESCRIPTION

10-1. Specification of keyboard control

1)Input Buffer Capacity: 64 bytes

Key-in data is written to the input buffer first, and is supplied to the CPU, byte by byte.

When an overflow is detected, the overflow code is affired to the key-in data already sent, before being sent to the CPU.

2)Rollover

2 key rollover (exemption in the CTRL mode)

(Entry of the second key depression can be accepted even if more than one key is pressed at same time.)

Simultaneous depression of more than three keys is ingnored.

3)Key bounce

15msec (Key spec is5-10msec)

(Indicates unstable state as shown in Fig. 3-2 that key signal does not turn off immediately after releasing of finger from the key.)

4)Key

5msec (norma), 20msec (max), 15msec (allows for key bounce)

5)DEF Key

Twenty definable keys are available in combination with the CTRL key.

[ DFK1-DFK10(DEF1A-DEF10A) DEF1-DFK10 in conjunction with the CTRL key

-- - (DEFIB-DEF10B)- (DEF1B-DBF10B)

6)Handling of functional symbols and graphic symbols See the code table.

7)Use of the CTRL key to discriminate RUN and CONT of the DEB key.

Push the DEB in conjunction with the CTRL key to start running.

8)Handling of special codes

COPY command: CTRL 1 J (ten key)

ESCape CTRL

BRKCTRL

9)PRO/OP

Sent to the CPU after power on and when PRO/OP is changed.

10)HOME key

CTRL [ HOME] Returns home after clearing the display screen.

[HOME] Only the cursor returns home.

11) One-step commands

 

uior

LMU /

rnlNI

LML) o

INrU T

UMU 4

USING

pft/in "7 .

(jU I U

pr\ci ID

 

Kb 1 UnN

 

Lib 1

PMH n .

 

PMn A

At rrn

 

ULUbt

PMH n -

n ATA

 

nrUnMA 1 fF

CMU K.

K.hY IN

PMH i

i OAH

r*Mn r\ -

 

 

nhAU

PMH c

CA\/C

12) Mode indication on LED

Acrn

i nr^w

13)REP

Key repetition will take place when a key depressed for more than 0.64second. Entry of other keys is permitted during key repetition. When two keys are depresssd at the same time, an alternate key entry will not be accepted. This rule does not apply to simultaneous depression of more than three keys.

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Page 83
Image 83
Sharp MZ-3500 service manual Specification of keyboard control, At rrn, Key