VOGONS

XT 8Mhz Turbo Board - Turbo Problem

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First post, by ciernioo

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Hello ! This is my first post on Vogons, so warm greetings to everyone ! I`m an ethusiast of old PC and 8-bit hardware. I have few builds of my own - I`ll be glad to show them here in near future... Anyway, I`m writing because I have a little problem with my last purchase: a very nice XT clone motherboard manufactured by Limco:

http://oi62.tinypic.com/2pqj380.jpg

The problem is I can`t enable the full 8Mhz the board has to offer - it boots only in standard 4.77Mhz. I`ve located the board on Total Hardware, it seems this is the one:

http://museum.ttrk.ee/th99/m/U-Z/31728.htm

I can`t understand the connections table, where they say that JP5 , JP6 and JP7 are all "Turbo switch". I`ve tried some combinations, but it seems that JP6 and JP7 don`t do much, and closing JP5 crashes the system. Does anyone know how to enable turbo on this board ? Or maybe the board is somehow broken ?? I`ll appreciate any help, thanks !!

My Z80 computer project http://ciernioo.wordpress.com/

Reply 1 of 3, by n1mr0d

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Seems to correspond to a single pole, double throw switch. Have you tried to connect JP5-JP6, or JP7,JP6?

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Reply 2 of 3, by dosquest

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Actually, looking at the sheet it looks as if those are headers for an actual "turbo" button and not a jumper slow, now it is my understanding that a switch, in its very fundamental being is a completion of a circuit, so maybe bridging one of the headers with a jumper will get you a permanent 8mhz boost..though it also said it could go 8 or 10mhz, I don't know if you want the 10mhz.

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Reply 3 of 3, by ciernioo

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It seems the problem has been resolved - the situation is : JP7 colsed & JP6 open enables software control over turbo function (key combination). JP7 open & Jp6 closed enables hardware control via JP5 : open= normal 4.77 , closed= 8Mhz. The case is closed, but maybe someone could use this information in the future ...

Also: JP1 is reset button. It is not mentoined anywhere on the page, but I`ve checked it.

My Z80 computer project http://ciernioo.wordpress.com/

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