INMC 80 News

  

February-April 1981, Issue 3











Page 15 of 55











-15-

The link LK1 must be left in’ the internal position (to select internal decoding [OEXT must now be connected to ![ORQ), Now with ILIOEXT lo A2 selects between the internal ports, while IOEXT hi disables the on board ports as it should.

To make this modification disconect pin 2 of [C45 and pin 5. of 1C4G by cutting the tracks on the component side, then join these two points together and to the IOEXT line at LK1, on the solder side. You can then build your 10 board with the following decoding:

EF AX 3F > AVTo GoLOFisH FEEDER ports (ia- IF) 6 2 p——> Fo DerecroR ports Cie -17)

a3

> PoweR Supply SmoKE DETECTOR porns

A (8-F)

1 © p-————_> Text Nascom poars (@-7) yorq

Yours faithfully,

D. Ritchie,

Circuit Diagram for modifying RAM A

See “32K – 48K Expansion’ article.

1C37p8 ‘

1C36 p2 1C39a 1C38b J t Es RAS Ic36p13. #9 kd IC 40 – £7 +5V —, 8x4116 1€38= 741502 Y Pe 1K 1C39 = 7632 * | « —s IC 32 p13 € Ls od MREQ.RFSH | | 1C3 p13 + * * * & a” Pa a“ MRE AIL # connections made by ‘piggybacking’ 1C40 on {C12, 410n13 etc except pind which are commoned to JC39 pin8 8 ps9 —

New decode pad 1038 1€38d 1€39c


This is an OCR’d version of the scanned page and likely contains recognition errors.











Page 15 of 55