From 52d5501842652c56faa1ab3e4a0901ae1e30e1a3 Mon Sep 17 00:00:00 2001
From: ripsaw8080 <ripsaw8080@users.sourceforge.net>
Date: Thu, 27 Sep 2018 20:07:06 +0000
Subject: [PATCH] Disable UMB on PCjr machine type; fixes broken MCB chain.
 Remove 128k PCjr faking from r2417 that was effectively disabled by r3420.

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@4164
---
 src/dos/dos_execute.cpp  |  8 --------
 src/dos/dos_memory.cpp   | 13 +++----------
 src/dos/dos_programs.cpp |  4 +---
 3 files changed, 4 insertions(+), 21 deletions(-)

diff --git a/src/dos/dos_execute.cpp b/src/dos/dos_execute.cpp
index ba02cc51..b27decdb 100644
--- a/src/dos/dos_execute.cpp
+++ b/src/dos/dos_execute.cpp
@@ -356,14 +356,6 @@ bool DOS_Execute(char * name,PhysPt block_pt,Bit8u flags) {
 			maxsize=0xffff;
 			/* resize to full extent of memory block */
 			DOS_ResizeMemory(pspseg,&maxsize);
-			/* now try to lock out memory above segment 0x2000 */
-			if ((real_readb(0x2000,0)==0x5a) && (real_readw(0x2000,1)==0) && (real_readw(0x2000,3)==0x7ffe)) {
-				/* MCB after PCJr graphics memory region is still free */
-				if (pspseg+maxsize==0x17ff) {
-					DOS_MCB cmcb((Bit16u)(pspseg-1));
-					cmcb.SetType(0x5a);		// last block
-				}
-			}
 		}
 		loadseg=pspseg+16;
 		if (!iscom) {
diff --git a/src/dos/dos_memory.cpp b/src/dos/dos_memory.cpp
index 8cdd810f..b8d6a33f 100644
--- a/src/dos/dos_memory.cpp
+++ b/src/dos/dos_memory.cpp
@@ -50,14 +50,7 @@ void DOS_FreeProcessMemory(Bit16u pspseg) {
 		if (mcb.GetPSPSeg()==pspseg) {
 			mcb.SetPSPSeg(MCB_FREE);
 		}
-		if (mcb.GetType()==0x5a) {
-			/* check if currently last block reaches up to the PCJr graphics memory */
-			if ((machine==MCH_PCJR) && (mcb_segment+mcb.GetSize()==0x17fe) &&
-			   (real_readb(0x17ff,0)==0x4d) && (real_readw(0x17ff,1)==8)) {
-				/* re-enable the memory past segment 0x2000 */
-				mcb.SetType(0x4d);
-			} else break;
-		}
+		if (mcb.GetType()==0x5a) break;
 		if (GCC_UNLIKELY(mcb.GetType()!=0x4d)) E_Exit("Corrupt MCB chain");
 		mcb_segment+=mcb.GetSize()+1;
 		mcb.SetPt(mcb_segment);
@@ -307,10 +300,10 @@ bool DOS_FreeMemory(Bit16u segment) {
 
 
 void DOS_BuildUMBChain(bool umb_active,bool ems_active) {
-	if (umb_active  && (machine!=MCH_TANDY)) {
+	if (umb_active  && (!IS_TANDY_ARCH)) {
 		Bit16u first_umb_seg = 0xd000;
 		Bit16u first_umb_size = 0x2000;
-		if(ems_active || (machine == MCH_PCJR)) first_umb_size = 0x1000;
+		if(ems_active) first_umb_size = 0x1000;
 
 		dos_infoblock.SetStartOfUMBChain(UMB_START_SEG);
 		dos_infoblock.SetUMBChainState(0);		// UMBs not linked yet
diff --git a/src/dos/dos_programs.cpp b/src/dos/dos_programs.cpp
index 41853a30..f2231815 100644
--- a/src/dos/dos_programs.cpp
+++ b/src/dos/dos_programs.cpp
@@ -441,9 +441,7 @@ public:
 
 		Bit16u seg,blocks;blocks=0xffff;
 		DOS_AllocateMemory(&seg,&blocks);
-		if ((machine==MCH_PCJR) && (real_readb(0x2000,0)==0x5a) && (real_readw(0x2000,1)==0) && (real_readw(0x2000,3)==0x7ffe)) {
-			WriteOut(MSG_Get("PROGRAM_MEM_CONVEN"),0x7ffe*16/1024);
-		} else WriteOut(MSG_Get("PROGRAM_MEM_CONVEN"),blocks*16/1024);
+		WriteOut(MSG_Get("PROGRAM_MEM_CONVEN"),blocks*16/1024);
 
 		if (umb_start!=0xffff) {
 			DOS_LinkUMBsToMemChain(1);